Liquid crystal alignment layer

ABSTRACT

There is provided a liquid crystal alignment layer comprising an alignment layer; and chemically bound to said alignment layer, a transport material. Also provided are methods for forming the liquid crystal alignment layer and the use thereof in displays for electronic apparatus.

[0001] This application is a continuation-in-part of Ser. No. 09/898,749filed Jul. 3, 2001 and claims priority from GB Application No. 0115987.0filed Jun. 29, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal alignment layersuitable for use in displays for electronic products and a method offorming the liquid crystal alignment layer and displays.

[0004] 2. Prior Art

[0005] Modern consumer electronics require cheap, high-contrast displayswith good power efficiency and low drive voltages. Particularapplications include displays for mobile phones and hand-held computers.Liquid crystal displays are often used for this purpose and lightemitting polymers displays are also of interest for this purpose.

SUMMARY OF THE INVENTION

[0006] Conventional liquid crystal displays (LCD) comprise a liquidcrystal alignment layer for aligning the liquid crystal. The alignmentlayer is typically made of an electrical insulator. Light emittingdisplays (e.g. made by the in situ polymerization of reactive mesogens)also require alignment such as by the use of aligning materials (e.g.polyimide) which, if as is usual, are insulating can impair theefficiency of the device. The Applicants have now found that a number ofbenefits may be achieved by enhancing the electrical conductivity of thealignment layer by the inclusion of a transport material therein.

[0007] In one aspect, enhancing the electrical conductivity of thealignment layer can reduce adverse residual dc effects in liquid crystaldisplay cells. These arise as a result of poorly balanced dc driveschemes that leave a small charge in the cell, which can induce imagesticking e.g. in active matrix-addressed LCDs. The adverse effects aremore frequently observed in ferroelectric liquid crystal (FLC) cellswhere dc imbalance is more likely to occur. The presence of a conductingalignment layer enables residual dc to discharge, thereby reducing theadverse affects.

[0008] In another aspect, in FLC cells the switching of the spontaneouspolarisation charge produces significant charge within the cell. Thischarge tends to counter the effect of any electric field applied toalign the liquid crystal molecules therein and thereby adversely reduceor eliminate any bistability in the display cell. The presence of aconducting alignment layer tends to reduce this adverse effect.

[0009] In a further aspect, where an electroluminescent material is usedas the light emitting backlight of the LCD, the electrical conductivityof the alignment layer has been found to enhance the electroluminescenceof the material used as the backlight for the LCD.

[0010] The Applicants have found that including (e.g. by doping) atransport material into the alignment layer produces the desiredenhancement in electrical conductivity thereof, but that when used inliquid crystal cells the transport material can tend to migrate into theliquid crystal. This migration reduces the resistivity of the liquidcrystal, which then undesirably draws more current. In the case ofactive matrix addressed displays, the RC time constant of the liquidcrystal can also be undesirably reduced. The Applicants have found thatthese potential negatives can be ameliorated by chemically binding thetransport material to the alignment layer.

[0011] According to one aspect of the present invention there isprovided a liquid crystal alignment layer comprising an alignment layer;and chemically bound to said alignment layer, a transport material.

[0012] In one aspect, the alignment layer is a photoalignment layer,that is to say an alignment layer comprised of materials that photoalign(e.g. by cross-linking or ablation) to form anisotropic layers whenpolarised light (e.g. UV) is applied.

[0013] Suitable photoalignment layers typically comprises a chromophoreattached to a sidechain polymer backbone by a flexible spacer entity.Suitable chromophores include cinnamates or coumarins, includingderivatives of 6 or 7-hydroxycoumarins. Suitable flexible spacerscomprise organic chains (e.g. unsaturated), including e.g. aliphatic,amine or ether linkages.

[0014] A typical sidechain photoalignment polymer containing coumarin asthe photoreactive group has the formula:

[0015] An exemplary photoalignment layer comprises the 7-hydroxycoumarincompound having the formula:

[0016] Other suitable materials for use in photoalignment layers aredescribed in M. O'Neill and S. M. Kelly, J. Phys. D. Appl. Phys. [2000],33, R67.

[0017] In aspects, the photoalignment layer is photocurable. This allowsfor flexibility in the angle at which the light emitting polymer (e.g.as a liquid crystal) is alignable and thus flexibility in itspolarization characteristics.

[0018] In another aspect, the alignment layer is a polyimide layer. Thelayer may be formed by dissolving polyamic acid in cyclopentanone oranother aggressive solvent and then coating onto a substrate followed byheating. The polyimide layer is largely insoluble in most conventionalsolvents.

[0019] When subjected to high energy (short wavelength e.g. 360 nm) UVlight polyimide is degraded. Where plane polarised UV light is employedthe polyimide may be degraded in one direction only to provide aunidirectionally aligned layer which may be used to align liquidcrystals.

[0020] The polyimde layer may be in the form of a rubbed polyimidelayer.

[0021] In a further aspect, nylon (e.g. in the form of rubbed nylon) maybe used as the alignment layer, typically in the form of a thin film(e.g. <100 nm film thickness). Nylon is particularly useful for aligningferroelectric liquid crystals.

[0022] Suitable nylon layers may be formed by dissolving Nylon 6 (say0.1-1% by weight) in a solvent such as formic acid, m-cresol or2-chloroethanol. This is then applied to a substrate (e.g byspin-coating) followed by heating to drive off the solvent and leave athin nylon film that can then be rubbed to cause alignment thereof.

[0023] In a further aspect, the alignment layer comprises a cross-linkedpolymer layer formed by deposition of a curable reactivemonomer/oligomer onto a surface followed by photo or thermalcross-linking thereof. The cross-linked polymer layer is typicallyrubbed to obtain the necessary alignment. It is also possible that itcould be treated with polarised UV light to create alignment.

[0024] Suitable oligomers include acrylated polyurethane and acrylatedpolyesters. A particular oligomer is that commercially available fromCiba Geigy under the trade name Ebecryl. Photo or thermal initiators mayalso be employed to initiate the cross-linking of the polymer layer.

[0025] In a further aspect, the alignment layer comprises a side chainliquid crystal polymer. A particular polymer of this type comprises theformula:

[0026] In a further aspect, the alignment layer comprises a reactiveliquid crystal formed from a reactive mesogen. A particular reactivemesogen has the formula:

[0027] The reactive liquid crystal is typically formed by coating onto asubstrate, drying and curing within the liquid crystal phase to form ananisotropic polymer film. In these cases the liquid crystal polymer orreactive mesogen is coated onto a conventional alignment layer. Thesubsequent coating is typically used to impart some special propertysuch as a different surface energy.

[0028] In a further aspect, the alignment layer comprises a gratingstructure. Such grating structures are for example, employed in theZenithal (trade name) bistable device (ZBD). Typical grating structurescomprise thick alignment films having ribbed structures. The films aregenerally formed from UV cured material.

[0029] The alignment layer comprises a transport material chemicallybound to said alignment layer. The transport material acts such as toincrease the electrical conductivity of the alignment layer. Thealignment layer is typically an electrical insulator in the absence ofthe transport material.

[0030] The transport material may be an ion, hole or electron transportcompound. By transport material it is meant a material that is capableof transporting the named species through an otherwise electricallyinsulating material.

[0031] Suitable ion transport compounds include mono- and di-reactiveion transport materials.

[0032] An exemplary mono-reactive ion transport material has theformula:

[0033] An exemplary di-reactive ion transport material has the formula:

[0034] Suitable hole transport compounds include triarylamine. Examplesof suitable triarylamines include those described in C. H. Chen, J. Shi,C. W. Tang, Macromol Symp. [1997] 125, 1.

[0035] One exemplary hole transport compound has the formula:

[0036] Another exemplary hole transport compound is4,4′,4″-tris[N-(1-napthyl)-N-phenyl-amino]triphenylamine which has theformula:

[0037] In aspects, the hole transport compound has a tetrahedral(pyramidal) shape which acts such as to controllably disrupt thealignment characteristics of the layer in a limited manner.

[0038] In one aspect, the photoalignment layer includes a copolymerincorporating both linear rod-like hole-transporting and photoactiveside chains.

[0039] The alignment layer and transport material thereof are chemicallybound. In one aspect, the alignment polymer is in the form of across-linked polymer network with the transport material as a boundcomponent thereof.

[0040] According to another aspect of the present invention there isprovided a liquid crystal cell comprising an inert substrate; andpresent on said inert substrate, a liquid crystal alignment layer asdescribed hereinbefore.

[0041] The alignment layer is typically formed on an inert substratesuch as a glass or plastic substrate. Indium tin oxide (ITO) coatedglass is a preferred substrate. The layer may be applied to thesubstrate by any suitable coating method. Spin-coating is a preferredcoating method herein.

[0042] The coating thickness is typically in the range from 10 to 500nm, particularly 20 to 200 nm.

[0043] According to other aspects of the present invention there areprovided methods for making liquid crystal display cells. In aspects,the chemical bond between the alignment layer and transport material maybe formed by reacting the constituents together prior to applying thelayer to a substrate, or the bond may be formed by an in situ reactionon a substrate. The reaction (e.g. a co-polymerisation) may in aspectsbe heat or UV light initiated with known photo or thermal initiatorcompounds being employed as necessary.

[0044] According to another aspect of the present invention there isprovided a liquid crystal display comprising a driver for driving thedisplay; and a liquid crystal cell as described herein before. Theliquid crystal display is suitably in the form of a ferroelectric liquidcrystal (FLC) display.

[0045] In a particular aspect herein, the alignment layer is aphotoalignment layer having a light emitting polymer aligned thereon. Inthis aspect, the transport material is preferably a hole and/or anelectron transport compound. Compound 8 is a preferred hole transportcompound for this application.

[0046] Suitably, the light emitting polymer is a polymer having a lightemitting chromophore. Suitable chromophores include fluorene,vinylenephenylene, anthracene and perylene. Useful chromophores aredescribed in A. Kraft, A. C. Grimsdale and A. B. Holmes, Angew. Chem.Int. Ed. Eng. [1998], 37, 402.

[0047] Suitably, the light emitting polymer is a liquid crystal whichcan be aligned to emit polarised light. A suitable class of polymers isbased on fluorene.

[0048] In one aspect, the light emitting polymer comprises an organiclight emitting diode (OLED) such as described in S. M. Kelly, Flat PanelDisplays: Advanced Organic Materials, RSC Materials Monograph, ed. J. A.Connor, [2000]; C. H. Chen, J. Shi, C. W. Tang, Macromol Symp. [1997]125, 1; R. H. Friend, R. W. Gymer, A. B. Holmes, J. H. Burroughes, R. N.Marks, C. Taliani, D. D. C. Bradley, D. A. Dos Santos, J. L. Bredas, M.Logdlund, W. R. Salaneck, Nature [1999] 397, 121; M. Grell, D. D. C.Bradley, Adv. Mater. [1999] 11, 895; N. C. Greenman, R. H. Friend SolidState Phys. [1995] 49, 1.

[0049] OLEDs may be configured to provide polarized electroluminescence.

[0050] The reactive mesogen (monomer) typically has a molecular weightof from 400 to 2,000. Lower molecular weight monomers are preferredbecause their viscosity is also lower leading to enhanced spin coatingcharacteristics and shorter annealing times which aids processing. Thelight emitting polymer typically has a molecular weight of above 4,000,typically 4,000 to 15,000.

[0051] The light emitting polymer typically comprises from 5 to 50,preferably from 10 to 30 monomeric units.

[0052] The light emitting polymer is aligned on the photoalignmentlayer. Suitably, the photoaligned polymer comprises uniaxially alignedchromophores. Typically polarization ratios of 30 to 40 are required,but with the use of a clean up polarizer ratios of 10 or more can beadequate for display uses.

[0053] In aspects, the light emitting polymer is formed by apolymerization process. Suitable processes involve the polymerization ofreactive mesogens (e.g. in liquid crystal form) via photo-polymerizationor thermal polymerization of suitable end-groups of the mesogens. Inpreferred aspects, the polymerization process results in cross-linkinge.g. to form an insoluble, cross-linked network. The polymerizationprocess can in a preferred aspect be conducted in situ after depositionof the reactive mesogens on the photoalignment layer by any suitabledeposition process including a spin-coating process.

[0054] In a preferred polymerization process, the light emitting polymeris formed by photopolymerization of reactive mesogens having photoactiveend-groups.

[0055] Suitable reactive mesogens have the following general structure:

B-S-A-S-B  (General formula 1)

[0056] wherein

[0057] A is a chromophore;

[0058] S is a spacer; and

[0059] B is an endgroup which is susceptible to radicalphotopolymerisation.

[0060] The polymerisation typically results in a light emitting polymercomprising arrangements of chromophores (e.g. uniaxially aligned) spacedby a crosslinked polymer backbone. The process is shown schematically inFIG. 1 from which it may be seen that the polymerisation of reactivemonomer 10 results in the formation of crosslinked polymer network 20comprising crosslink 22, polymer backbone 24 and spacer 26 elements.

[0061] Suitable chromophore (A) groups have been described previously.Suitable spacer (S) groups comprise unsaturated organic chains,including e.g. flexible aliphatic, amine or ether linkages. Aliphaticspacers are preferred. The presence of spacer groups aids the solubilityand lowers the melting point of the light emitting polymer which assiststhe spin coating thereof.

[0062] Suitable endgroups are susceptible to photopolymerization (e.g.by a process using UV radiation, generally unpolarized). Preferably, thepolymerization involves cyclopolymerization (i.e. the radicalpolymerization step results in formation of a cyclic entity).

[0063] A typical polymerization process involves exposure of a reactivemesogen of general formula 1 to UV radiation to form an initial radicalhaving the general formula as shown below:

B-S-A-S-B.  (General formula 2)

[0064] wherein A, S and B are as defined previously and B. is aradicalised endgroup which is capable of reacting with another Bendgroup (particularly to form a cyclic entity). The B. radicalisedendgroup suitably comprises a bound radical such that the polymerisationprocess may be sterically controlled.

[0065] Suitable endgroups include dienes such as 1,4, 1,5 and 1,6dienes. The diene functionalities may be separated by aliphaticlinkages, but other inert linkages including ether and amine linkagesmay also be employed.

[0066] Methacrylate endgroups have been found to be less suitable thandienes because the high reactivity of the radicals formed after thephotoinitiation step can result in a correspondingly highphotodegradation rate. By contrast, it has been found that thephotodegradation rate of light emitting polymers formed from dienes ismuch lower. The use of methacrylate endgroups also does not result incyclopolymerization.

[0067] Where the endgroups are dienes the reaction typically involvescyclopolymerization by a sequential intramolecular and intermolecularpropagation: A ring structure is formed first by reaction of the freeradical with the second double bond of the diene group. A double ring isobtained by the cyclopolymerization which provides a particularly rigidbackbone. The reaction is in general, sterically controlled.

[0068] Suitable reactive mesogens have the general formula:

[0069] wherein R has the general formula: X-S2-Y-Z

[0070] and wherein

[0071] X=O, CH₂ or NH and preferably X=O;

[0072] S2=linear or branched alkyl or alkenyl chain optionally includinga heteroatom (e.g. O, S or NH) and preferably S2=a linear alkyl chain;

[0073] Y=O, CO₂ or S and preferably Y=CO₂; and

[0074] Z=a diene (end-group) and preferably Z=a 1,4, 1,5 or 1,6 diene.

[0075] Exemplary reactive mesogens have the general formula:

[0076] wherein R is selected from:

[0077] An exemplary reactive mesogen has the formula:

[0078] All of Compounds 9 to 12 exhibit a nematic phase with a clearingpoint (N-I) between 79 and 120° C.

[0079] Other suitable exemplary reactive mesogens have the generalformula:

[0080] wherein n is from 2 to 10, preferably from 3 to 8 and wherein, asabove, R has the general formula: X-2-Y-Z

[0081] and wherein

[0082] X=O, CH₂ or NH and preferably X=O;

[0083] S2=linear or branched alkyl or alkenyl chain optionally includinga heteroatom (e.g. O, S or NH) and preferably S2=a linear alkyl chain;

[0084] Y=O, CO₂ or S and preferably Y=CO₂; and

[0085] Z=a diene (end-group) and preferably Z=a 1,4, 1,5 or 1,6 diene.

[0086] Suitably, R is as for any of Compounds 9 to 12, as shown above.

[0087] A particular class of exemplary reactive mesogens has theformula:

[0088] wherein:

[0089] n is from 2 to 10, preferably from 3 to 8; and

[0090] m is from 4 to 12, preferably from 5 to 11.

[0091] Still further suitable exemplary reactive mesogens have thegeneral formula:

[0092] wherein A=H or F

[0093] and wherein, as above, R has the general formula: X-S2-Y-Z

[0094] and wherein

[0095] X=O, CH₂ or NH and preferably X=O;

[0096] S2=linear or branched alkyl or alkenyl chain optionally includinga heteroatom (e.g. O, S or NH) and preferably S2=a linear alkyl chain;

[0097] Y=O, CO₂ or S and preferably Y=CO₂; and

[0098] Z=a diene (end-group) and preferably Z=a 1,4, 1,5 or 1,6 diene.

[0099] Suitably, R is as for any of Compounds 9 to 12, as shown above.

[0100] Particular exemplary reactive mesogens of this type have theformula:

[0101] In aspects, the preferred photopolymerization process can beconducted at room temperature, thereby minimizing any possible thermaldegradation of the reaction mesogen or polymer entities.Photopolymerization is also preferable to thermal polymerization becauseit allows subsequent sub-pixellation of the formed polymer bylithographic means.

[0102] Further steps may be conducted subsequent to the polymerizationprocess including doping and the addition of other layers (as describedin more detail below).

[0103] The light emitting polymer may be aligned by a range of methodsincluding the use of polyimide. However, standard polyimide alignmentlayers are insulators, giving rise to low charge injection for OLEDs.

[0104] The susceptibility to damage of the alignment layer during thealignment process can be reduced by the use of a non-contactphotoalignment method. In such methods, illumination with polarizedlight introduces a surface anisotropy to the alignment layer and hence apreferred in-plane orientation to the overlying light emitting polymer(e.g. in liquid crystal form).

[0105] The aligned light emitting polymer is in one aspect in the formof an insoluble nematic polymer network. Cross-linking has been found toimprove the photoluminescence properties.

[0106] M. O'Neill, S. M. Kelly J. Appl. Phys. D [2000] 33, R67 providesa review of photoalignment materials and methods.

[0107] In one particular aspect, herein a transport material (suitablycomprising a methacrylate end-group) is co-polymerised with a knownalignment layer (e.g. a coumarin alignment layer, such as one comprisingCompound 2) to form a transporting (e.g. hole transporting) alignmentcopolymer layer.

[0108] Particular examples of such copolymers include:

[0109] wherein, for each of Compounds 25 to 27, 0<x<1 (i.e. x is greaterthan 0 and less than 1) and n is from 5 to 500, preferably from 10 to30.

[0110] The emitter herein may comprise additional layers such asadditional carrier transport layers. The presence of anelectron-transporting polymer layer (e.g. comprising an oxadiazole ring)has been found to increase electroluminescence.

[0111] An exemplary electron transporting polymer has the formula:

[0112] Pixellation of the light emitter may be achieved by selectivephotopatterning to produce red, green and blue pixels as desired. Thepixels typically have a size of from 1 to 500 μm. In microdisplays, thepixels have a size of from 1 to 50 μm, preferably from 5 to 15 μm, suchas from 8 to 10 μm. In other displays, the pixel size is typicallylarger with a size of about 300 μm being typical.

[0113] The layers may also be doped with photoactive dyes. In aspects,the dye comprises a dichroic or pleachroic dye. Examples includeanthraquinone dyes or tetralines, including those described in S. M.Kelly, Flat Panel Displays: Advanced Organic Materials, RSC MaterialsMonograph, ed. J. A. Connor, [2000]. Different dopant types can be usedto obtain different pixel colors.

[0114] Pixel color can also be influenced by the choice of chromophorewith different chromophores having more suitability as red, green orblue pixels, for example using suitably modified anthraquinone dyes.

[0115] Multicolor emitters are envisaged herein comprising arrangementsor sequences of different pixel colors.

[0116] One suitable multicolor emitter comprises stripes of red, greenand blue pixels having the same polarization state. This may be used asa sequential color backlight for a display which allows the sequentialflashing of red, green and blue lights. Such backlights can be used intransmissive FLC displays where the FLC acts as a shutter for theflashing colored lights.

[0117] Another suitable multicolor emitter comprises a full colorpixelated display in which the component pixels thereof have the same ordifferent alignment.

[0118] Suitable multicolor emitters may be formed by a sequential ‘coat,selective cure, wash off’ process in which a first color emitter isapplied to the aligned layer by a suitable coating process (e.g. spincoating). The coated first color emitter is then selectively cured onlywhere pixels of that color are required. The residue (of uncured firstcolor emitter) is then washed off. A second color emitter is thenapplied to the aligned layer, cured only where pixels of that color arerequired and the residue washed off. If desired, a third color may beapplied by repeating the process for the third color.

[0119] The above process may be used to form a pixelated display such asfor use in a color emissive display. This process is simpler thantraditional printing (e.g. ink jet) methods of forming such displays.

[0120] In one aspect there is provided a backlight for a displaycomprising a power input; and a photoalignment layer comprising a lightemitter as described hereinbefore.

[0121] The backlight may be arranged for use with a liquid crystaldisplay. In aspects, the backlight may be monochrome or multicolor.

[0122] In one aspect there is provided a display comprising a screen;and a light emitter or backlight as described hereinbefore.

[0123] The screen may have any suitable shape or configuration includingflat or curved and may comprise any suitable material such as glass or aplastic polymer.

[0124] The light source of the present invention has been found to beparticularly suitable for use with screens comprising plastic polymerssuch as polyethylene or polyethylene terephthalate (PET).

[0125] The display is suitable for use in consumer electronic goods suchas mobile telephones, hand-held computers, watches, clocks and gamesmachines.

[0126] In one aspect there is provided a security viewer (e.g. in kitform) comprising a light emitter as described herein in which the pixelsare arranged for polarized emission; and view glasses having a differentpolarization for each eye.

[0127] In one aspect there is provided a method of forming a lightemitter for a display comprising forming a photoalignment layer herein;and aligning a light emitting polymer on said photoalignment layer.

[0128] In one aspect there is provided a method of forming a multicoloremitter comprising applying a first color light emitter is applied tothe photoalignment layer; selectively curing said first color lightemitter only where that color is required; washing off any residue ofuncured first color emitter; and repeating the process for a second andany subsequent light color emitters.

[0129] All references herein are incorporated by reference in theirentirety.

BRIEF DESCRIPTION OF THE DRAWINGS

[0130] Embodiments of systems according to the invention will now bedescribed with reference to the accompanying experimental detail anddrawings in which:

[0131]FIG. 1 is a schematic representation of a polymerization processherein;

[0132]FIG. 2 is a representation of a display device in accord with thepresent invention;

[0133]FIG. 3 is a representation of a backlight in accord with thepresent invention; and

[0134]FIG. 4 is a representation of a polarised sequential lightemitting backlight in accord with the present invention.

[0135] FIGS. 5 to 15 show reaction schemes 1 to 11, respectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0136] General Experimental Details

[0137] Fluorene, 2-(tributylstanyl)thiophene, 4-(methoxyphenyl)boronicacid and the dienes were purchased from Aldrich and used as received.Reagent grade solvents were dried and purified as follows.N,N-Dimethylformamide (DMF) was dried over anhydrous P₂O₅ and purifiedby distillation. Butanone and methanol were distilled and stored over 5Å molecular sieves. Triethylamine was distilled over potassium hydroxidepellets and then stored over 5 Å molecular sieves. Dichloromethane wasdried by distillation over phosphorus pentoxide and then stored over 5 Åmolecular sieves. Chloroform was alumina-filtered to remove any residualethanol and then stored over 5 Å molecular sieves. ¹H nuclear magneticresonance (NMR) spectra were obtained using a JOEL JMN-GX270 FT nuclearresonance spectrometer. Infra-red (IR) spectra were recorded using aPerkin Elmer 783 infra-red spectrophotometer. Mass spectral data wereobtained using a Finnegan MAT 1020 automated GC/MS. The purity of thereaction intermediates was checked using a CHROMPACK CP 9001 capillarygas chromatograph fitted with a 10 m CP-SIL 5CB capillary column. Thepurity of the final products was determined by high-performance liquidchromatography [HPLC] (5 □m, 25 cm×0.46 cm, ODS Microsorb column,methanol, >99%) and by gel-permeation chromatography [GPC] (5 □m, 30cm×0.75 cm, 2×mixed D PL columns, calibrated using polystyrene standards[molecular weights=1000-4305000], toluene; no monomer present). Thepolymers were found to exhibit moderate to high M_(w) values(10,000-30,000) and acceptable M_(w)/M_(n) values (1.5-3). The liquidcrystalline transition temperatures were determined using an OlympusBH-2 polarising light microscope together with a Mettler FP52 heatingstage and a Mettler FP5 temperature control unit. The thermal analysisof the photopolymerisable monomers (Compounds 3 to 6) and the mainchainpolymer (Compound 7) was carried out by a Perkin-Elmer Perkin-Elmer DSC7 differential scanning calorimeter in conjunction with a TAC 7/3instrument controller. Purification of intermediates and products wasmainly accomplished by column chromatography using silica gel 60(200-400 mesh) or aluminium oxide (Activated, Brockman 1, ˜150 mesh).Dry flash column chromatography was carried out using silica gel H(Fluka, 5-40 μm). Electroluminescent materials were further purified bypassing through a column consisting of a layer of basic alumina, a thinlayer of activated charcoal, a layer of neutral alumina and a layer ofHi-Flo filter aid using DCM as an eluent. This was followed byrecrystallisation from an ethanol-DCM mixture. At this stage, allglass-wear was thoroughly cleaned by rinsing with chromic acid followedby distilled water and then drying in an oven at 100° C. for 45 minutes.Purity of final products was normally confirmed by elemental analysisusing a Fisons EA 1108 CHN apparatus.

[0138] Key intermediate 1:2,7-bis[5-(4-hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene wassynthesised as shown in Reaction Scheme 1. Full details each step arenow given:

[0139] 9-Propylfluorene: A solution of n-Butyllithium (18.0 cm³, 10Msolution in hexanes, 0.18 mol) was added slowly to a solution offluorene (30.0 g, 0.18 mol) in THF (350 cm³) at −50° C. The solution wasstirred for 1 h at −75° C. and 1-bromopropane (23.0 g, 0.19 mol) wasadded slowly. The solution was allowed to warm to RT and then stirredfor a further 1 h. Dilute hydrochloric acid (100 cm³, 20%) and water(100 cm³) were added and the product extracted into diethyl ether (3×150cm³). The ethereal extracts were dried (MgSO₄) and concentrated to apale yellow oil (37.5 g, yield 100%). Purity 100% (GC).

[0140]¹H NMR (CD₂Cl₂) δ: 7.75 (2H, dd), 7.52 (2H, m), 7.32 (4H, m), 3.98(1H, t), 1.95 (2H, m), 1.19 (2H, m), 0.85 (3H, t). IR (KBr pellet cm⁻¹):3070 (m), 2962 (s), 1450 (s), 1296 (w), 1189 (w), 1030 (w), 938 (w), 739(s). MS (m/z): 208 (M⁺), 178, 165 (M100), 139.

[0141]9,9-Dipropylfluorene: A solution of n-Butyllithium (29.0 cm³, 2.5Msolution in hexanes, 0.073 mol) was added slowly to a solution of9-propylfluorene (15.0 g, 0.072 mol) in THF at −50° C. The solution wasstirred for 1 h at −75° C., 1-bromopropane (10.0 g, 0.092 mol) was addedslowly and the temperature raised to RT after completion of theaddition. After 18 h, dilute hydrochloric acid (20%, 100 cm³) and water(100 cm³) were added and the product extracted into diethyl ether (2□100 cm³). The ethereal extracts were dried (MgSO₄) and concentrated toa pale brown oil which crystallised overnight at RT. The product waspurified by recrystallisation from methanol to yield a white crystallinesolid (14.5 g, yield 80%) mp 47-49° C. (Lit. 49-50° C.¹⁹). Purity 100%(GC).

[0142]¹H NMR (CDCl₃) δ: 7.68 (2H, m), 7.31 (6H, m), 1.95 (4H, t), 0.65(10H, m).IR (KBr pellet cm-1): 3068 (m), 2961 (s), 1449 (s), 1293 (w),1106 (w), 1027 (w), 775 (m), 736 (s), 637 (m). MS (m/z): 250 (M⁺), 207(M100), 191, 179, 165.

[0143] 2,7-Dibromo-9,9-dipropylfluorene: Bromine (10.0 g, 0.063 mol) wasadded to a stirred solution of 9,9-dipropylfluorene (7.0 g, 0.028 mol)in chloroform (25 cm³) and the solution purged with dry N₂ for 0.5 h.Chloroform (50 cm³) was added and the solution washed with saturatedsodium bisulphite solution (75 cm³), water (75 cm³), dried (MgSO₄) andconcentrated to a pale yellow powder (11.3 g, yield 98%) mp 134-137° C.

[0144]¹H NMR (CDCl₃) δ: 7.51 (2H, d), 7.45 (4H, m), 1.90 (4H, t), 0.66(10H, m). IR (KBr pellet cm⁻¹): 2954 (s), 1574 (w), 1451 (s), 1416 (m),1270 (w), 1238 (w), 1111 (w), 1057 (s), 1006 (w), 931 (w), 878 (m), 808(s), 749 (m). MS (m/z): 409 (M⁺), 365, 336, 323, 284, 269, 256, 248,202, 189, 176 (M100), 163.

[0145] 2,7-bis(Thien-2-yl)-9,9-dipropylfluorene: A mixture of2,7-dibromo-9,9-dipropylfluorene (6.0 g, 0.015 mol),2-(tributylstannyl)thiophene (13.0 g, 0.035 mol) andtetrakis(triphenylphosphine)-palladium (0) (0.3 g, 2.6×10⁴ mol) in DMF(30 cm³) was heated at 90° C. for 24 h. DCM (200 cm³) was added to thecooled reaction mixture and the solution washed with dilute hydrochloricacid (2□150 cm³, 20%), water (100 cm³), dried (MgSO₄) and concentratedonto silica gel for purification by column chromatography [silica gel,DCM:hexane 1:1]. The compound was purified by recrystallisation fromDCM: ethanol to yield light green crystals (4.3 g, yield 6 9%), mp165-170° C. Purity 100% (GC).

[0146]¹H NMR (CDCl₃) δ: 7.67 (2H, d), 7.60 (2H, dd), 7.57 (2 h, d), 7.39(2H, dd), 7.29 (2H, dd), 7.11 (2H, dd), 2.01 (4H, m), 0.70 (10H, m). IR(KBr pellet cm⁻¹): 2962 (m), 2934 (m), 2872 (m), 1467 (m), 1276 (w),1210 (m), 1052 (w), 853 (m), 817 (s), 691 (s). MS (m/z): 414 (M⁺, M100),371, 342, 329, 297, 207, 165.

[0147] 2,7-bis(5-Bromothien-2-yl)-9,9-dipropylfluorene:N-Bromosuccinimide (2.1 g, 0.012 mol freshly purified byrecrystallisation from water) was added slowly to a stirred solution of2,7-bis(thien-2-yl)-9,9-dipropylfluorene (2.3 g, 5.55×10⁻³ mol) inchloroform (25.0 cm³) and glacial acetic acid (25.0 cm³). The solutionwas heated under reflux for 1 h, DCM (100 cm³) added to the cooledreaction mixture, washed with water (100 cm³), HCl (150 cm³, 20%),saturated aqueous sodium bisulphite solution (50 cm³), and dried(MgSO₄). The solvent was removed in vacuo and the product purified byrecrystallisation from an ethanol-DCM mixture to yield yellow-greencrystals (2.74 g, yield 86%). mp 160-165° C.

[0148]¹H NMR (CDCl₃) δ: 7.66 (2H, d), 7.49 (2H, dd), 7.46 (2H, d), 7.12(2H, d), 7.05 (2H, d), 1.98 (4H, t), 0.69 (10H, m). IR (KBr pelletcm⁻¹): 3481 (w), 2956 (s), 1468 (s), 1444 (m), 1206 (w), 1011 (w), 963(w), 822 (m), 791 (s), 474 (w). MS (m/z): 572 (M⁺), 529, 500, 487, 448,433, 420, 407, 375, 250, 126.

[0149] 2,7-bis[5-(4-Methoxyphenyl)thien-2-yl]-9,9-dipropylfluorene: Amixture of 2,7-bis(5-bromothien-2-yl)-9,9-dipropylfluorene (2.7 g,4.7×10⁻³ mol), 4-(methoxyphenyl)boronic acid (2.15 g, 0.014 mol),tetrakis(triphenylphosphine)palladium (0) (0.33 g, 2.9×10⁻⁴ mol), sodiumcarbonate (3.0 g, 0.029 mol) and water (20 cm³) in DME (100 cm³) washeated under reflux for 24 h. More 4-(methoxyphenyl)boronic acid (1.0 g,6.5×10⁻³ mol) was added to the cooled reaction mixture, which was thenheated under reflux for a further 24 h. DMF (20 cm³) was added and thesolution heated at 110° C. for 24 h, cooled and dilute hydrochloric acid(100 cm³, 20%) added. The cooled reaction mixture was extracted withdiethyl ether (230 cm³) and the combined ethereal extracts washed withwater (100 cm³), dried (MgSO₄), and concentrated onto silica gel to bepurified by column chromatography [silica gel, DCM:hexane 1:1] andrecrystallisation from an ethanol-DCM mixture to yield a greencrystalline solid (1.86 g, yield 63%), Cr-N, 2350C; N-I, 265° C.

[0150]¹H NMR (CD₂Cl₂) δ: 7.71 (2H, dd), 7.61 (8H, m), 7.37 (2H, d), 7.24(2H, d), 6.95 (4H, d), 3.84 (6H, s), 2.06 (4H, m), 0.71 (10H, m). IR(KBr pellet cm⁻¹): 2961 (w), 1610 (m), 1561 (m), 1511 (s), 1474 (s),1441 (m), 1281 (m), 1242 (s), 1170 (s), 1103 (m), 829 (m), 790 (s). MS(m/z): 584 (M⁺-C₃H₇), 569, 555, 539, 525, 511, 468, 313, 277 (M100),248, 234. Elemental analysis. Calculated: wt % C=78.56%, H, 6.11%, S,10.23%. Found: C, 78.64%, H, 6.14%, S, 10.25%

[0151] 2,7-bis[5-(4-Hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene): A1M solution of boron tribromide in chloroform (9 cm³, 9.0 mmol) wasadded dropwise to a stirred solution of2,7-bis[5-(4-methoxyphenyl)thien-2-yl]-9,9-dipropylfluorene (1.3 g,2.1×10⁻³ mol) at 0° C. The temperature was allowed to rise to RTovernight and the solution added to ice-water (200 cm³) with vigorousstirring. The product was extracted into diethyl ether (220 cm³), washedwith aqueous sodium carbonate (2M, 150 cm³), dried (MgSO₄) and purifiedby column chromatography [silica gel DCM:diethyl ether:ethanol 40:4:1]to yield a green solid (1.2 g, yield 96%), Cr-I, 277° C.; N-I, 259° C.

[0152]¹H NMR (d-acetone) δ: 8.56 (2H, s), 7.83 (2H, dd), 7.79 (2H, d),7.68 (2H, dd), 7.57 (4H, dd), 7.50 (2H, dd), 7.31 (2H, dd), 6.91 (4H,dd), 2.15 (4H, m), 0.69 (10H, m). IR (KBr pellet cm⁻¹): 3443 (s, broad),2961 (m), 1610 (m), 1512 (m), 1474 (m), 1243 (m), 1174 (m), 1110 (w),831 (m), 799 (s). MS (m/z): 598 (M⁺), 526, 419 (M100), 337.

[0153] Compound 9:2,7-bis(5-{4-[5-(1-Vinyl-allyloxycarbonyl)pentyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene:The 1,3-pentadiene monomer (Compound 9) was synthesised as depicted inReaction Scheme 2. Full details of each step are now given:

[0154] 1,4-Pentadien-3-yl 6-bromohexanoate: A solution of6-bromohexanoyl chloride (3.2 g, 0.026 mol) in DCM (30 cm³) was addeddropwise to a solution of 1,4-pentadien-3-ol (2.0 g, 0.024 mol) andtriethylamine (2.4 g, 0.024 mol) in DCM (30 cm³). The mixture wasstirred for 1 h and washed with dilute hydrochloric acid (20%, 50 cm³),saturated potassium carbonate solution (50 cm³), water (50 cm³) thendried (MgSO₄) and concentrated to a brown oil. The product was purifiedby dry flash chromatography [silica gel, DCM] to yield a pale yellow oil(4.7 g, yield 75%). Purity>95% (GC).

[0155]¹H NMR (CDCl₃) δ: 5.82 (2H, m), 5.72 (1H, m), 5.30 (2H, d), 5.27(2H, d), 3.42 (2H, t), 2.37 (2H, t), 1.93 (2H, m), 1.72 (2H, m), 1.54(2H, m). IR (KBr pellet cm⁻¹): 3095 (w), 1744 (s), 1418 (w), 1371 (w),12521 (m), 1185 s), 983 (m), 934 (m). MS (m/z): 261 (M⁺), 177, 67.

[0156] 2,7-bis(5-{4-[5-(1-Vinyl-allyloxycarbonyl)pentyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene: A mixture of2,7-bis[5-(4-hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene (0.6 g,1.0×10⁻³ mol), 1,4-pentadien-3-yl 5-bromohexanoate (0.7 g, 2.7×10⁻³ mol)and potassium carbonate (0.5 g, 3.6×10⁻³ mol) in acetonitrile (25 cm³)was heated at 50° C. for 18 h. The mixture was then heated under refluxconditions for a further 20 h. Excess potassium carbonate was filteredoff and precipitated product rinsed through with DCM (230 cm³). Thesolution was concentrated onto silica gel for purification by columnchromatography [silica gel, DCM:hexane 1:1 gradients to DCM] andrecrystallisation from a DCM-ethanol mixture to yield a green-yellowsolid (0.4 g, yield 40%), Cr-N, 92° C.; N-I, 108° C.

[0157]¹H NMR (CD₂Cl₂) δ: 7.69 (2H, d), 7.58 (8H, m), 7.35 (2H, d), 7.22(2H, d), 6.91 (4H, d), 5.83 (4H, m), 5.68 (2H, m), 5.29 (2H, t), 5.25(2H, t), 5.21 (2H, t), 5.19 (2H, t), 3.99 (4H, t), 2.37 (4H, t), 2.04(4H, m), 1.80 (4H, quint), 1.70 (4H, quint), 1.51 (4H, quint) 0.69 (10H,m). IR (KBr pellet cm⁻¹): 2936 (m), 2873 (m), 1738 (s), 1608 (m), 1511(m), 1473 (s), 1282 (m), 1249 (s), 1177 (s) 1110 (m), 982 (m), 928 (m),829 (m), 798 (s). APCI-MS (m/z): 958 (M⁺), 892 (M100). Elementalanalysis. Calculated: wt % C=76.37, wt % H=6.93, wt % S=6.68. Found: wt% C=75.93, wt % H=6.95, wt % S=6.69.

[0158] Compound 10:2,7-bis(5-{4-[5-(1-Allylbut-3-enyloxycarbonyl)pentyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene:

[0159] The 1,3-heptadiene monomer (Compound 10) was synthesised asdepicted in reaction Scheme 3. Full details of each step are now given:

[0160] 1,6-Heptadien-5-yl 5-bromopentanoate: 5-Bromopentanoyl chloride(3.0 g, 0.015 mol) was added dropwise to 1,6-heptadien-4-ol (1.5 g,0.013 mol) and triethylamine (1.4 g, 0.014 mol) in DCM (25 cm³). Themixture was stirred for 2 h and washed with dilute hydrochloric acid(20%, 50 cm³), saturated aqueous potassium carbonate solution (50 cm³),water (50 cm³) then dried (MgSO₄) and concentrated to a brown oil. Theproduct was purified by dry flash chromatography [silica gel, DCM] toyield a pale yellow oil (1.7 g, yield 48%). Purity>92% (GC).

[0161]¹H NMR (CDCl₃) δ: 5.74 (2H, m), 5.08 (4H, m), 4.99 (1H, m), 3.41(2H, t), 2.31 (6H, m), 1.88 (2H, m), 1.76 (2H, m). IR (Film cm⁻¹): 2952(m), 1882 (w), 1734 (s), 1654 (m) 1563 (w), 1438 (m), 1255 (m), 1196(s), 996 (m), 920 (s). MS (m/z): 275 (M⁺), 245, 219, 191, 183, 163(M100), 135, 95, 79.

[0162]2,7-bis(5-{4-[5-(1-Allylbut-3-enyloxycarbonyl)pentyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene:A mixture of 2,7-bis[5-(4-hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene(0.3 g, 1.0×10⁻³ mol), 1,6-heptadienyl 6-bromohexanoate (0.7 g, 2.7×10⁻³mol) and potassium carbonate (0.5 g, 3.6×10⁻³ mol) in acetonitrile (25cm³) was heated under reflux for 20 h. Excess potassium carbonate wasfiltered off and precipitated product rinsed through with DCM (230 cm³).The solution was concentrated onto silica gel for purification by columnchromatography [silica gel, DCM: hexane 1:1 gradients to DCM] andrecrystallisation from a DCM-ethanol mixture to yield a green-yellowsolid (0.21 g, yield 21%), Cr-I, 97° C., N-I, 94° C.

[0163]¹H NMR (CDCl₃) δ: 7.68 (2H, d), 7.60 (2H, dd), 7.58 (2H, d), 7.57(2H, d), 7.33 (2H, d), 7.20 (2H, d), 6.91 (2H, d), 5.75 (4H, m), 5.08(8H, m), 5.00 (2H, quint), 4.00 (4H, t), 2.33 (12H, m), 2.02 (4H, t),1.82 (4H, quint), 1.71 (4H, quint), 1.53 (4H, m), 0.72 (10H, m). IR (KBrpellet cm⁻¹): 3443 (s), 2955 (s), 1734 (s), 1643 (w), 1609 (m), 1512(m), 1473 (s), 1249 (s), 1178 (s), 996 (m), 918 (m), 829 (m), 799 (s).APCI-MS (m/z): 1015 (M⁺, M100), 921. Elemental analysis. Calculated: wt% C, 76.89, wt % H=7.35, wt % S=6.32%. Found: wt % C=76.96, wt % H=7.42,wt % S=6.23.

[0164] Compound 11:2,7-bis(5-{4-[3-(1-Vinylallyloxycarbonyl)propyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene

[0165] The 1,3-pentadiene homologue (Compound 11) was synthesised asdepicted in reaction Scheme 4. Full details of each step are now given:

[0166] 4-Bromobutanoyl chloride: Oxalyl chloride (15.2 g, 0.12 mol) wasadded dropwise to a stirred solution of 4-bromobutanoic acid (10.0 g,0.060 mol) and DMF (few drops) in chloroform (30 cm³). The solution wasstirred overnight under anhydrous conditions and concentrated to a palebrown oil which was filtered to remove solid impurities (11.0 g, yield99%).

[0167] 1,4-Pentadien-3-yl 4-bromobutanoate: 4-Bromobutanoyl chloride(3.0 g, 0.016 mol) was added dropwise to a solution of1,4-pentadien-3-ol (1.3 g, 0.015 mol) and triethylamine (1.5 g, 0.015mol) in DCM (30 cm³). The solution was stirred for 2 h and washed withdilute hydrochloric acid (20%, 50 cm³), saturated potassium carbonatesolution (50 cm³), water (50 cm³) then dried (MgSO₄) and concentrated toa pale brown oil. The product was purified by dry flash chromatography[silica gel, DCM] to yield a pale yellow oil (1.8 g, yield 51%).Purity>85% (GC; decomposition on column).

[0168]¹H NMR (CDCl₃) δ: 5.83 (2H, m), 5.72 (1H, m), 5.27 (4H, m), 3.47(2H, t), 2.55 (2H, t), 2.19 (2H, quint). IR (KBr pellet cm⁻¹): 3096 (w),2973 (w), 1740 (s), 1647 (w), 1419 (m), 1376 (m), 1198 (s), 1131 (s),987 (s), 932 (s), 557 (w). MS (m/z) 217, 166, 152, 149, 125, 110, 84, 67(M100).

[0169] 2,7-bis(5-{4-[3-(1-Vinylallyloxycarbonyl)propyloxy]phenyl}thien-2-yl)-9,9-dipropylfluorene: A mixture of2,7-bis[5-(4-hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene (0.25 g,4.2×10⁻⁴ mol), 1,4-pentadien-3-yl 4-bromobutanoate (0.40 g, 1.7×10⁻³mol) and potassium carbonate (0.20 g, 1.4×10⁻³ mol) in DMF (10 cm³) washeated under reflux for 4 h. The cooled solution was filtered, rinsedthrough with DCM (3×20 cm³) and concentrated to a pale green oil whichwas purified by column chromatography [silica gel, DCM:hexane 2:1]followed by recrystallisation from ethanol:DCM to yield a green-yellowpowder (0.20 g, yield 53%), Cr-N, 92° C.; N-I, 116° C.

[0170]¹H NMR (CDCl₃) δ: 7.61 (10H, m), 7.33 (2H, d), 7.20 (2H, d), 6.92(4H, d), 5.85 (4H, m), 5.74 (2H, m), 5.32 (4H, d, J=17 Hz), 5.24 (4H, d,J=10 Hz), 4.06 (4H, t), 2.56 (4H, t), 2.16 (4H, quint), 2.05 (4H, t),0.72 (10H, m). IR (KBr pellet cm⁻¹): 3449 (m), 2960 (m), 1738 (s), 1609(m), 1512 (m), 1473 (s), 1380 (w), 1249 (s), 1174 (s), 1051 (m), 936(m), 830 (m), 799 (s). APCI-MS (m/z): 903 (M⁺), 837 (M100), 772.Elemental analysis. Calculated: wt % C=75.80, wt % H=6.47, wt % S=7.10.Found: wt % C=76.13, wt % H=6.48%, wt % S=6.91.

[0171] Compound 12:2,7-bis{5-[4-(8-Diallylaminooctyloxy)phenyl]-thien-2-yl}-9,9-dipropylfluorene

[0172] The method of preparation of the N,N-diallylamine monomer(Compound 12) is shown in reaction Scheme 5. Full details of each stepare now given:

[0173] 8-Diallylaminooctan-1-ol. A mixture of 8-bromooctan-1-ol (10.0 g,0.048 mol), diallylamine (4.85 g, 0.050 mol) and potassium carbonate(7.0 g, 0.051 mol) in butanone (100 cm³) was heated under reflux for 18h. Excess potassium carbonate was filtered off and the solutionconcentrated to a colourless oil. The product was purified by dry flashchromatography [silica gel, DCM:ethanol 4:1]. (10.0 g, yield 93%)

[0174]¹H NMR (CDCl₃) δ: 5.86 (2H, d), 5.14 (4H, m), 3.71 (4H, quart),3.63 (4H, t), 3.09 (4H, d), 1.56 (4H, m), 1.45 (2H, quint), 1.30 (6H,m). IR (KBr pellet cm⁻¹): 3344 (s), 2936 (s), 1453 (w), 1054 (m), 998(m), 921 (m). MS (m/z): 225 (M⁺), 198, 184, 166, 152, 138, 124, 110(M100), 81.

[0175] Toluene-4-sulphonic acid 8-diallylaminooctyl ester.4-Toluene-sulphonyl chloride (12.5 g, 0.066 mol) was added slowly to astirred solution of 8-diallylaminooctan-1-ol (10.0 g, 0.044 mol) andpyridine (7.0 g, 0.088 mol) in chloroform (100 cm³) at 0° C. After 24 h,water (100 cm³) was added and the solution washed with dilutehydrochloric acid (20%, 100 cm³), sodium carbonate solution (100 cm³),water (100 cm³), dried (MgSO₄) and concentrated to a yellow oil whichwas purified by column chromatography [silica gel, 4% diethyl ether inhexane eluting to DCM:ethanol 10:1] to yield the desired product (6.7 g,yield 40%).

[0176]¹H NMR (CDCl₃) δ: 7.78 (2H, d), 7.34 (2H, d), 5.84 (2H, m), 5.13(4H, m), 4.01 (2H, t), 3.41 (4H, d), 2.45 (3H, s), 2.39 (2H, t), 1.63(2H, quint), 1.42 (2H, quint), 1.30 (2H, quint), 1.23 (6H, m). IR (KBrpellet cm⁻¹): 3454 (w), 2957 (m), 1453 (s), 1402 (m), 1287 (m), 1159(w), 1061 (m), 914 (w), 878 (m), 808 (s), 448 (m). MS (m/z): 380 (M⁺),364, 352, 338, 224, 110 (M100), 91, 79, 66.

[0177]2,7-bis{5-[4-(8-Diallylaminooctyloxy)phenyl]-thien-2-yl}-9,9-dipropylfluorene:A mixture of 2,7-bis[5-(4-hydroxyphenyl)thien-2-yl]-9,9-dipropylfluorene(0.5 g, 8.4×10⁻⁴ mol), toluene-4-sulphonic acid-8-diallylaminooctylester (0.8 g, 2.1×10⁻³ mol) and potassium carbonate (0.3 g, 2.2×10⁻³mol) in butanone (30 cm³) was heated under reflux for 24 h. Excesspotassium carbonate was filtered off and rinsed with DCM (3×30 cm³). Thesolution was concentrated onto silica gel for purification by columnchromatography [silica gel, DCM:hexane 2:1 eluting to DCM:ethanol 4:1].The product was obtained as a yellow-green glass (0.35 g, yield 41%),N-I, 95° C.

[0178]¹H NMR (CDCl₃) δ: 7.67 (2H, d), 7.58 (8H, m), 7.34 (2H, d), 7.20(2H, d), 6.92 (4H, d), 5.94 (4H, m), 5.25 (8H, m), 3.99 (4H, t), 3.22(8H, d), 2.02 (4H, t), 1.80 (4H, quint), 1.56 (4H, quint), 1.47 (4H,quint), 1.35 (12H, m), 0.71 (10H, m). IR (KBr pellet cm⁻¹): 3437 (s),(2934 (s), 1609 (s), 1512 (s), 1472 (s), 1283 (m), 1249 (s), 1179 (s),1031 (w), 918 (w), 829 (m), 798 (s). APCI-MS (m/z): 1014 (M⁺, M100),973. Elemental analysis. Calculated: wt % C=79.40, wt % H=8.35, wt %N=2.76, wt % S, 6.33. Found: wt % C=79.33, wt % H=8.29, wt % N=2.88, wt% S=6.17.

[0179] Compound 13:poly(phenylene-1,3,4-oxadiazole-phenylene-hexafluoropropylene)

[0180] The electron-transporting polymer (Compound 13) was preparedaccording to a literature method described in Li, X. -C.; Kraft, A.;Cervini, R.; Spencer, G. C. W.; Cacialli, F.; Friend, R. H.; Gruener,J.; Holmes, A. B.; de Mello, J. C.; Moratti, S. C. Mat. Res. Symp. Proc.1996, 413 13.

[0181] In more detail the preparation details were as follows: Asolution of 4,4′-(hexafluoroisopropylidine)bis(benzoic acid) (2.54 g,6.48×10⁻³ mol) and hydrazine sulphate (0.84 g, 6.48×10⁻³ mol) in Eaton'sreagent (25 cm³) was heated under reflux for 18 h. The cooled solutionwas added to brine (300 cm³) and the product extracted into chloroform(8×200 cm³). The organic extracts were combined, dried (MgSO₄) and thesolvent removed under reduced pressure to yield the crude product whichwas purified by dissolving in a minimum volume of chloroform andprecipitating by dropwise addition to methanol (1000 cm³). Theprecipitate was filtered off and washed with hot water before beingdried in vacuo. The precipitation was repeated a further three timeswashing with methanol each time. The product was then dissolved inchloroform and passed through a microfilter (0.45 μm). The pure productwas then precipitated in methanol (500 cm³) and the methanol removedunder reduced pressure to yield a white fibrous solid which was dried invacuo. Yield 1.26 g (50%).

[0182]¹H NMR (CDCl₃) δ_(H): 8.19 (4H/repeat unit, d), 7.61 (4H/repeatunit, d). IR ν_(max)/cm⁻¹: 3488 (m), 1621 (m), 1553 (m), 1502 (s), 1421(m), 1329 (m), 1255 (s), 1211 (s), 1176 (s), 1140 (s), 1073 (m), 1020(m), 969 (m), 929 (m), 840 (m), 751 (m), 723 (s). GPC:M_(w):M_(n)=258211:101054.

[0183] An alternative electron-transport copolymer is prepared accordingto the method described in Xiao-Chang Li et al J. Chem. Soc. Chem.Commun., 1995, 2211.

[0184] In more detail the preparation details were as follows:Terephthaloyl chloride (0.50 g, 2.46×10⁻³ mol) was added to hydrazinehydrate (50 cm³) at room temperature and the mixture stirred for 2 h.The precipitate was filtered off, washed with water (100 cm³) and driedin vacuo. The crude hydrazide (0.25 g, 1.3×10⁻³ mol),4,4′-(hexafluoroisopropylidine)bis(benzoic acid) (2.50 g, 6.4×10⁻³ mol)and hydrazine sulphate (0.66 g, 5.2×10⁻³ mol) were added to Eaton'sreagent and the resultant mixture heated at 100° C. for 24 h. Thereaction mixture was added to water (300 cm³) and the product extractedinto chloroform (3×300 cm³). The organic extracts were combined, dried(MgSO₄) and the solvent removed in vacuo before re-dissolving theproduct in the minimum volume of chloroform. The solution was addeddropwise to methanol (900 cm³) to give a white precipitate which wasfiltered off and dried in vacuo. The precipitation was repeated twicebefore dissolving the product in chloroform and passing through amicrofilter (0.45 μm) into methanol (500 cm³). The methanol was removedunder reduced pressure and the product dried in vacuo. Yield 1.1 g (41%)

[0185]¹H NMR (CDCl₃) δ_(H): 8.18 (dd, 4H/repeat unit), 7.60 (dd,4H/repeat unit). IR ν_(max)/cm⁻¹: 3411 (w), 2366 (w), 1501 (m), 1261(s), ¹²¹I (s), 1176 (s), 1140 (m), 1072 (m), 1021 (w), 968 (m), 931 (w),840 (m), 722 (m). GPC: M_(w):M_(n)=20572:8320.

[0186] Key intermediate 2:9,9-diethyl-2,7-bis(4-hydroxybiphenyl-4′-yl)fluorene was synthesised asshown in Reaction Scheme 7. Full details of each step are now given:

[0187] 9-Ethylfluorene: A solution of n-butyllithium (79.52 cm³, 0.2168mol, 2.5M in hexane) was added slowly to a solution of fluorene (30.00g, 0.1807 mol) in THF (300 cm³) at −70° C. The solution was stirred for1 hour at −75° C. and 1-bromoethane (17.59 cm³, 0.2349 mol) was addedslowly. The solution was allowed to warm to room temperature and thenstirred overnight. Dilute hydrochloric acid (200 ml, 20%) was added tothe reaction mixture and stirred for a further 10 minutes. Water (250cm³) was added and the product extracted into diethyl ether (3×300 cm³).The combined organic extracts were dried (MgSO₄) and the solvent removedon a rotary evaporator. The resulting oil was purified by distillationto yield a pale yellow oil (25.00 g, 71%, b.pt.-150° C.@1 mbar Hg).

[0188]¹H NMR (DMSO) δ: 7.70 (2H, m), 7.50 (2H, m), 7.30 (4H, m), 4.00(1H, t), 2.02 (2H, quart), 0.31 (3H, t). IR ν_(max)/cm⁻¹: 3072 (m),2971, 1618, 1453, 1380, 1187, 759, 734. MS m/z: 170 (M⁺), 94, 82, 69.

[0189] 9,9-Diethylfluorene: A solution of n-butyllithium (77.34 cm³,0.1934 mol, 2.5M in hexane) was added slowly to a solution of9-ethylfluorene (25.00 g, 0.1289 mol) in THF (250 cm³) at −70° C. Thesolution was stirred for 1 hour at −75° C. and 1-bromoethane (17.59 cm³,0.1934 mol) was added slowly. The solution was allowed to warm to roomtemperature and then stirred overnight. Dilute hydrochloric acid (200cm³, 20%) was added to the reaction mixture and stirred for a further 10minutes. Water (250 cm³) was added and the product extracted intodiethyl ether (3×300 cm³). The combined organic extracts were dried(MgSO₄) and the solvent removed on a rotary evaporator. The resultingoil was cooled to room temperature and recrystallised with ethanol toyield white crystals (19.50 g, 68%, m.pt. 60-62° C.).

[0190]¹H NMR (DMSO) δ: 7.76 (2H, m), 7.51 (2H, m), 7.35 (4H, m), 1.51(4H, quart), 0.30 (6H, t), IR ν_(max)/cm⁻¹: 3069, 2972, 1612, 1448,1310, 761, 736. MS m/z: 222 (M⁺), 193, 152, 94, 82, 75.

[0191] 2,7-Dibromo-9,9-diethylfluorene: Bromine (13.47 cm³, 0.2568 mol)was added to a stirred solution of 9,9-diethylfluorene (19.00 g, 0.0856mol) in DCM (250 cm³). The HBr gas evolved was passed through ascrubbing solution of NaOH (1.5M). The reaction mixture was stirred for4 hours. The reaction mixture was washed with sodium metabisulphitesolution and extracted into diethyl ether (3×300 cm³). The combinedorganic extracts were dried and the solvent removed on a rotaryevaporator. The crude product was recrystallised from ethanol to yield awhite crystalline solid (20.00 g, 61%, m.pt. 152-154° C.).

[0192]¹H NMR (DMSO) δ: 7.52 (2H, m), 7.45 (4H, m), 1.99 (4H, quart),0.31 (6H, t). IR ν_(max)/cm⁻¹: 2966, 1599, 1453, 1418, 1058, 772, 734.MS m/z: 380 (M⁺), 351, 272, 220, 189, 176, 165, 94, 87, 75.

[0193] 4-Bromo-4′-octyloxybiphenyl: A mixture of4-bromo-4′-hydroxybiphenyl (50.00 g, 0.2008 mol), 1-bromooctane (50.38g, 0.2610 mol), potassium carbonate (47.11 g, 0.3414 mol) and butanone(500 cm³) was heated under reflux overnight. The cooled mixture wasfiltered and the solvent removed on a rotary evaporator. The crude solidwas recrystallised from ethanol to yield a white crystalline solid(47.30 g, 66%, m.pt. 120° C.).

[0194]¹H NMR (DMSO) δ: 7.46 (6H, m), 6.95 (2H, m), 3.99 (2H, t), 1.80(2H, quint), 1.38 (10H, m), 0.88 (3H, t). IR ν_(max)/cm⁻¹: 2927, 2860,1608, 1481, 1290, 1259, 844. MS m/z: 362 (M⁺), 250, 221, 195, 182, 152,139, 115, 89, 76, 69.

[0195] 4-Octyloxybiphenyl-4′-yl boronic acid: A solution ofn-butylithium (50.97 cm³, 0.1274 mol, 2.5M in hexane) was added dropwiseto a cooled (−78° C.) stirred solution of 4-bromo-4′-octyloxybiphenyl(40.00 g, 0.1108 mol) in THF (400 cm³). After 1 h, trimethyl borate(23.05 g, 0.2216 mol) was added dropwise to the reaction mixturemaintaining a temperature of −78° C. The reaction mixture was allowed towarm to room temperature overnight. 20% hydrochloric acid (350 cm³) wasadded and the resultant mixture stirred for 1 h. The product wasextracted into diethyl ether (3×300 cm³). The combined organic layerswere washed with water (300 cm³), dried (MgSO₄), filtered and thefiltrate evaporated down under partially reduced pressure. The crudeproduct was stirred with hexane for 30 minutes and filtered off to yielda white powder (26.20 g, 73%, m.pt. 134-136° C.).

[0196]¹H NMR (DMSO) δ: 8.04 (2H, s), 7.84 (2H, m), 7.57 (4H, m), 7.00(2H, m), 3.99 (2H, t), 1.74 (2H, quint), 1.35 (10H, m), 0.85 (3H, t). IRν_(max)/cm⁻¹: 2933, 2860, 1608, 1473, 1286, 1258, 818. MS m/z: 326 (M⁺),214, 196, 186, 170, 157, 128, 115, 77, 63

[0197] 9,9-Diethyl-2,7-bis(4-octyloxybiphenyl-4′-yl)fluorene:

[0198] Tetrakis(triphenylphosphine)palladium(0) (0.70 g, 0.0006 mol) wasadded to a stirred solution of 2,7-dibromo-9,9-diethylfluorene (4) (2.33g, 0.0061 mol), 4-octyloxybiphenyl-4′-yl boronic acid (5.00 g, 0.0153mol), 20% sodium carbonate solution (100 cm³) and 1,2-dimethoxyethane(150 cm³). The reaction mixture was heated under reflux overnight. Water(300 cm³) was added to the cooled reaction mixture and the productextracted into DCM (3×300 cm³). The combined organic extracts werewashed with brine (2×150 cm³), dried (MgSO₄)), filtered and the filtrateevaporated down under partially reduced pressure. The residue waspurified by column chromatography on silica gel using DCM and hexane(30:70) as eluent and recrystallisation from ethanol and DCM to yield awhite crystalline solid (3.10 g, 65%, m.pt. 146° C.).

[0199]¹H NMR (DMSO) δ: 7.77 (6H, m), 7.63 (12H, m), 7.00 (4H, m), 4.01(4H, t), 2.13 (4H, quart), 1.82 (4H, quint), 1.40 (20H, m), 0.89 (6H,t), 0.43 (6H, t). IR ν_(max)/cm⁻¹: 3024, 2921, 2853, 1609, 1501, 1463,1251, 808. MS m/z: 782 (M⁺), 669, 514, 485, 279, 145, 121, 107, 83, 71.CHN analysis: % Expected C (87.42%), H (8.49%). % Found C (87.66%), H(8.56%).

[0200] 9,9-Diethyl-2,7-bis(4-hydroxybiphenyl-4′-yl)fluorene: Borontribromide (99.9%, 1.05 cm³, 0.0111 mol) in DCM (10 ml) was addeddropwise to a cooled (0° C.) stirred solution of9,9-diethyl-2,7-bis(4-octyloxybiphenyl-4′-yl)fluorene (2.90 g, 0.0037mol) in DCM (100 cm³). The reaction mixture was stirred at roomtemperature overnight, then poured onto an ice/water mixture (50 g) andstirred (30 minutes). The crude product was purified by columnchromatography on silica gel with a mixture of ethyl acetate and hexane(30:70) as the eluent and recrystallisation from ethanol to yield awhite powder (0.83 g, 40%, m.pt.>300° C.).

[0201]¹H NMR (DMSO) δ: 9.09 (2H, OH), 7.77 (6H, m), 7.64 (8H, m), 7.51(4H, m), 6.94 (4H, m), 1.19 (4H, m), 0.42 (6H, t). IR ν_(max)/cm⁻¹:1608, 1500, 1463, 1244, 1173, 811. MS m/z: 558 (M⁺), 529, 514, 313, 279,257, 115, 77, 65.

[0202] Compound 14:9,9-Diethyl-2,7-bis{4-[5-(1-vinyl-allyloxycarbonyl)pentyloxy]biphenyl-4′-yl}fluorene:Compound 14 was synthesised as follows:

[0203] A mixture of 9,9-diethyl-2,7-bis(4-hydroxybiphenyl-4′-yl)fluorene(0.83 g, 0.0015 mol), 1,4-pentadienyl-3-yl 6-bromohexanoate (0.97 g,0.0037 mol), potassium carbonate (0.62 g, 0.0045 mol) and DMF (25 cm³)was heated under reflux overnight. The cooled reaction mixture was addedto water (500 cm³) and then extracted with DCM (3×50 cm³). The combinedorganic extracts were washed with water (250 cm³), dried (MgSO₄) and thefiltrate evaporated down under partially reduced pressure. The crudeproduct was purified by column chromatography using silica gel using amixture of DCM and hexane (80:20) as the eluent and recrystallisationfrom DCM and ethanol to yield a white crystalline solid (0.2 g, 22%).

[0204]¹H NMR (CDCl₃) δ: 7.78 (6H, m), 7.62 (12H, m), 7.00 (4H, m), 5.85(4H, m), 5.74 (4H, m), 5.27 (4H, m), 4.03 (4H, t), 2.42 (4H, t), 2.14(4H, quart), 1.85 (4H, m), 1.74 (4H, m), 1.25 (4H, q), 0.43 (3H, t). IRν_(max)/cm⁻¹: 3028, 2922, 2870, 1734, 1606, 1500, 1464, 1246, 1176, 812.CHN analysis: % Expected C (82.32%), H (7.24%). % Found C (81.59%), H(6.93%).

[0205] Compounds 15-21: Compounds 15 to 21, comprising the2,7-bis{ω-[5-(1-vinyl-allyloxycarbonyl)alkoxy]-4′-biphenyl}-9,9-dialkylfluorenescompounds of Table 1 were prepared analogously to Compound 8.

n m Compound 15 3 5 Compound 16 4 5 Compound 17 5 5 Compound 18 6 5Compound 19 8 5 Compound 20 8 7 Compound 21 8 11

[0206] Compound 22:4,7-bis{4-[(S)-3,7-Dimethyl-oct-6-enyloxy]phenyl}2,1,3-benzothiadozole

[0207] Compound 22 was synthesised as depicted in Reaction Scheme 8.Full details of each step follows:

[0208] 4,7-Dibromo-2,1,3-benzothiadozole: Bromine (52.8 g, 0.33 mol) wasadded to a solution of 2,1,3-benzothiadozole (8.1 g, 0.032 mol) inhydrobromic acid (47%, 100 cm³) and the resultant solution was heatedunder reflux for 2.5 h. The cooled reaction mixture reaction mixture wasfiltered and the solid product washed with water (200 cm³) and suckeddry. The raw product was purified by recrystallisation from ethanol toyield 21.0 g (65%) of the desired product.

[0209] 1-Bromo-4-[(S)-3,7-dimethyloct-6-enyloxy]benzene: A mixture of4-bromophenol (34.6 g, 0.20 mol), (S)-(+)-citronellyl bromide (50 g,0.023 mol) and potassium carbonate (45 g, 0.33 mol) in butanone (500cm³) was heated under reflux overnight. The cooled reaction mixture wasfiltered and the filtrate concentrated under reduced pressure. The crudeproduct was purified by fractional distillation to yield 42.3 g (68.2%)of the desired product.

[0210] 4-[(S)-3,7-Dimethyloct-6-enyloxy]phenyl boronic acid: 2.5Mn-Butylithium in hexanes (49.3 cm³, 0.12 mol) was added dropwise to acooled (−78° C.) solution of1-bromo-4-[(S)-3,7-dimethyloct-6-enyloxy]benzene (35 g, 0.11 mol) intetrahydrofuran (350 cm³). The resultant solution was stirred at thistemperature for 1 h and then trimethyl borate (23.8 g, 0.23 mol) wasadded dropwise to the mixture while maintaining the temperature at −78°C. 20% hydrochloric acid (250 cm³) was added and the resultant mixturewas stirred for 1 h and then extracted into diethyl ether (2×200 cm³).The combined organic layers were washed with water (2×100 cm³) and dried(MgSO₄). After filtration the solvent was removed under reduce pressureto yield 20.35 g (65%) of the desired product.

[0211] 4,7-bis{4-[(S)-3,7-Dimethyl-oct-6-enyloxy]phenyl}-2,1,3-benzothiadozole: A mixture oftetrakis(triphenylphosphine)palladium(0) (0.8 g, 0.70×10⁻³ mol),4,7-dibromo-2,1,3-benzothiadozole (2) (2 g, 6.75×10⁻³ mol),4-[(S)-3,7-dimethyloct-6-enyloxy]phenyl boronic acid (4.66 g, 1.70×10⁻²mol), 2M sodium carbonate solution (50 cm³) and 1,2-dimethoxyethane (150cm³). The reaction mixture was heated under reflux overnight. The cooledreaction mixture was extracted with dichloromethane (2×150 cm³) and thecombined organic layers were washed with brine (2×100 cm³) and dried(MgSO₄). After filtration the solvent was removed under reduced pressureand the residue was purified by column chromatography [silica gel,dichloromethane: hexane 1:4] followed by recrystallisation from ethanolto yield 3.2 g (79.5%) of the desired product.

[0212] 4,7-bis(4-Hydroxyphenyl)-2,1,3-benzothiadozole: Boron tribromide(1.51 cm³, 1.61×10⁻² mol) was added dropwise to a cooled (0° C.) stirredsolution of2,5-bis{4-[(S)-3,7-dimethyl-oct-6-enyloxy]phenyl}-2,1,3-benzothiadozole(4.0 g, 7.40×10⁻³ mol) in dichloromethane (100 cm³). The reactionmixture was stirred at room temperature overnight, then poured onto anice/water mixture (200 g) and stirred (30 min). The desired product wasprecipitated and it was filtered off and sucked dry to yield 1.23 g(71.5%) of the desired product.

[0213]4,7-bis(4-{5-[1-Vinyl-allyloxycarbonyl]pentyloxy}phenyl)-2,1,3-benzothiadozole:A mixture of 2,5-bis(4-hydroxyphenyl)-2,1,3-benzothiadozole (0.3 g,0.93×10⁻³ mol), 1,4-pentadien-3-yl 5-bromopentanoate (0.61 g, 2.34×10⁻³mol) and potassium carbonate (0.38 g, 2.79×10⁻³ mol) inN,N-dimethylformaldehyde (30 cm³) was heated (80° C.) overnight. Thecooled reaction mixture was filtered and the filtrate concentrated underreduce pressure. The crude product was purified by column chromatography[silica gel, ethyl acetate:hexane 1:5] followed by recrystallisationfrom ethanol to yield 0.39 g (61.8%) of the desired product.

[0214] Compounds 23 and 24 are preparable by an analogous process.

[0215] Compound 25: Poly(4-[6-(methylacryloyloxy)hexyloxy]benzoic Acid9,9-dioctyl-2-(4-nonylphenyl)fluoren-7-yl ester4-[6-(methacryloyloxy)hexyloxy]benzoic Acid 2-oxo-2H-chromen-7-yl Ester:

[0216] Compound 25 was prepared as shown in Reaction Scheme 9. Fulldetails of each step are as follows:

[0217] 2-Bromo-9,9-dioctyl-7-hydroxyfluorene: 2.5M n-butyllithium inhexanes (20.0 cm³, 0.05 mol) was added dropwise to a solution of2,7-dibromo-9,9-dioctylfluorene (20.0 g, 0.0364 mol) and tetrahydrofuran(300 cm³) maintaining a temperature of −70° C. After stirring for 1 h,trimethylborate (9.45 g, 0.09 mol) was added dropwise. After allowingthe solution to reach RT, 20% hydrochloric acid (100 cm³) was added andthe solution stirred for a further 1.5 h. The product was extracted intodiethyl ether (2×100 cm³) and the combined extracts washed with water(2×100 cm³), dried (MgSO₄) and concentrated to a pale yellow oil.Diethyl ether (200 cm³) and hydrogen peroxide (30%, 100 cm³) were addedand the solution heated under gentle reflux for 2.5 h with vigorousstirring. The ether layer was separated off and the aqueous layerextracted into diethyl ether (3×50 cm³). The combined organic layerswere washed with saturated sodium metabisulphite solution (2×100 cm³),dried (MgSO₄), filtered and evaporated down under slightly reducedpressure to a pale yellow oil, which was purified by columnchromatography [silica gel, dichloromethane:hexane:ethanol 50:50:1] andrecrystallisation from hexane to yield a white crystalline solid (yield7.80 g, 45%), GC: 99%, mpt 110° C.

[0218]¹H NMR (CDCl₃) δ_(H): 0.62 (6H, t), 0.82 (4H, m), 1.1 (20H, m)1.86 (4H, t), 4.70 (1H, s), 6.77 (2H, m), 7.43 (2H, d), 7.50 (2H, d). IRν_(max)/cm⁻¹: 3471, 3388, 2927.6, 2849, 1611, 1452, 1234, 1180, 816,528. MS m/z: 486, 484 (M⁺), 422, 211, 197, 122.

[0219] 2-Bromo-9,9-dioctyl-7-octyloxyfluorene: A mixture of2-bromo-9,9-dioctyl-7-hydroxyfluorene (6.00 g, 0.0124 mol),1-bromooctane (3.104 g, 0.0161 mol), potassium carbonate (3.41 g, 0.0247mol) and butanone (100 cm³) was heated under reflux overnight. Thecooled mixture was filtered and evaporated down under reduced pressure.The crude product was purified by column chromatography [silica gel,dichloromethane: hexane: 1:1] and then used without further purification(yield 5.04 g, 68.3%), GC: 99%.

[0220]¹H NMR (CDCl₃) δ_(H): 0.6 (6H, t), 0.82 (4H, m), 0.89 (6H), 1.2(25H, m), 1.49 (4H, sext), 1.85 (4H, m), 4.0 (2H, t), 6.85 (2H, m), 7.42(2H, m), 7.53 (2H, d) MS m/z: 598, 596 (M⁺), 519, 404, 292, 194.

[0221] 9,9-Dioctyl-2-(4-nonylphenyl)-7-octyloxyfluorene: A mixture oftetrakis(triphenylphosphine)palladium(0) (0.5 g, 4.64×10⁻⁴ mol),2-bromo-9,9-dioctyl-7-octyloxyfluorene (5.04 g, 0.00844 mol),4-nonylphenylboronic acid (2.30 g, 0.00929 mol), 20% aqueous sodiumcarbonate solution (40 cm³) and N,N-dimethylformamide (150 cm³) washeated under reflux overnight. The reaction mixture was filtered andextracted into diethyl ether (2×100 cm³). The combined organic layerswere washed with water (2×100 cm³), dried (MgSO₄), filtered and thesolvent removed under partially reduced pressure. The residue waspurified by column chromatography [silica gel, dichloromethane: hexane:30:70] (yield 3.65 g, 60.0%).

[0222]¹H NMR (CDCl₃) δ_(H): 0.66 (4H, t), 0.85 (14H, dt), 1.11 (20H, m),1.3 (23H, t), 1.5 (2H, quint), 1.65 (2H, quint), 1.87 (6H, m), 2.65 (2H,t), 4.2 (2H, t), 6.87 (2H, d), 7.26 (2H, d), 7.55 (6H, m). MS m/z: 720(M⁺), 608, 283.

[0223] 9,9-Dioctyl-2-hydroxy-7-(4-Nonylphenyl)fluorene: A 1 M solutionof boron tribromide in dichloromethane, (0.55 cm³, 0.00581 mol) wasadded dropwise to a stirred solution of9,9-dioctyl-2-(4-nonylphenyl)-7-octyloxyfluorene (2.79 g, 0.00388 mol)and dichloromethane (100 cm³) at 0° C. The temperature was allowed torise to RT overnight and the solution added to ice-water (200 cm³) withvigorous stirring. The product was extracted into diethyl ether (2×200cm³). The combined organic extracts were washed with saturated aqueoussodium carbonate solution (150 cm³), dried (MgSO₄), filtered and thesolvent removed under reduced pressure. The residue was purified bycolumn chromatography [silica gel, dichloromethane:hexane: 20:80] (yield2.2 g, 93.4%).

[0224]¹H NMR (CDCl₃) δ_(H): 0.66 (4H, t), 0.84 (9H, m), 1.10 (20H, m),1.30 (12H, d), 1.65 (2H, quint), 1.94 (4H, m), 2.65 (2H, t), 4.79 (1H,s), 6.80 (2H, m), 7.26 (2H, d), 7.56 (6H, m). IR ν_(max)/cm⁻¹: 2900,2850, 1450, 1250, 750. MS (m/z): 602 (M⁺), 495, 406, 283.

[0225] 4-[6-(Methylacryloyloxy)hexyloxy]benzoic acid9,9-dioctyl-2-(4-nonylphenyl)fluoren-7-yl ester: A solution ofN,N-dicyclohexylcarbodiimide (0.34 g, 0.0017 mol) in dichloromethane (20cm³) was added to a solution of9,9-dioctyl-2-hydroxy-7-(4-nonylphenyl)fluorene (1.0 g, 0.0017 mol),4-[6-(methylacryloyloxy)hexyloxy]benzoic acid (0.5 g, 0.0017 mol),4-(N,N-dimethyl)pyridine (0.2 g, 0.0017 mol) and dichloromethane (10cm³) at room temperature. The reaction mixture was stirred overnight,filtered and the filtrate evaporated down under reduced pressure. Thecrude product was purified by column chromatography [silica gel,dichloromethane:hexane:60:40] (yield 0.15 g, 10.1%).

[0226]¹H NMR (CDCl₃) δ_(H): 0.69 (3H, s), 0.85 (9H, m), 1.13 (26H,quint), 1.3 (24H, d), 1.58 (2H, d), 1.95 (4H, quint), 2.1 (3H, s), 2.66(2H, t), 5.77 (1H, t), 6.38 (1H, s), 7.1 (2H, d), 7.23 (6H, d), 7.56(4H, m), 7.69 (2H, m). IR ν_(max)/cm⁻¹: 2900, 2850, 1720, 1450, 1150,800. MS m/z: 789 (M100), 681, 677.

[0227] Poly(4-[6-(methylacryloyloxy)hexyloxy]benzoic acid9,9-dioctyl-2-(4-nonylphenyl)fluoren-7-yl ester4-[6-(methacryloyloxy)hexyloxy]benzoic acid 2-oxo-2H-chromen-7-yl ester:A solution of 4-[6-(methylacryloyloxy)hexyloxy]benzoic acid9,9-dioctyl-2-(4-nonylphenyl)fluoren-7-yl ester (0.10 g, 1.11×10⁻⁴ mol),4-[6-(methacryloyloxy)hexyloxy]benzoic acid 2-oxo-2H-chromen-7-yl ester(0.10 g, 2.22×10⁻⁴ mol), 1,1′-azobis(cyclohexanecabonitrile) (0.05 g)and toluene (10 cm³) was heated under reflux overnight. The reactionmixture was evaporated down and the residue taken up in a minimum ofdichloromethane. The resultant solution was poured into methanol (100cm³) and the resultant precipitate filtered off and dried by suction.This procedure was repeated several times before drying the productunder vacuum to yield the desired copolymer.

[0228] Compound 26: Poly 2-Methylacrylic Acid6-(4-benzothiazol-2-yl-2,6-dimethoxyphenoxy)hexyl ester4-[6-(methacryloyloxy)hexyloxy]benzoic Acid 2-oxo-2H-chromen-7-yl Ester

[0229] Compound 26 was prepared by copolymerisation of 2-Methylacrylicacid 6-(4-benzothiazol-2-yl-2,6-dimethoxyphenoxy)hexyl ester with4-[6-(methacryloyloxy)hexyloxy]benzoic acid 2-oxo-2H-chromen-7-yl esterin a method analogous to the copolymerisation step of Compound 25.

[0230] The initial reaction steps are shown in Reaction Scheme 10 andfull details are provided below.

[0231] 2-(3,4,5-Trimethoxyphenyl)benzothiazole: A solution of3,4,5-trimethoxybenzaldehyde (19.7 g, 0.1 mol), 2-aminobenzenethiol(11.2 cm³, 0.105 mol) and dimethylsulfoxide acid (75 cm³) was heatedunder reflux for 24 hours. The cooled solution was added to water andextracted into ethyl acetate (3×50 cm³). The combined organic layerswere dried (MgSO₄), filtered and the filtrate evaporated down underreduced pressure. The solid residue was recrystallised from ethylacetate to give 25.5 g (85.0%) of the desired product, mpt. 135° C.

[0232]¹H NMR (CDCl₃) δ_(H): 3.83 (3H, s), 3.95 (6H, s), 7.33 (2H, s),7.41 (1H, td), 7.51 (1H, td), 7.99 (1H, d), 8.02 (1H, d). Elementalanalysis: Calculated: C, 63.77, H, 5.02, N, 4.65, S, 10.64; Found: C,63.54; H, 5.02; N, 465 , S, 10.70%.

[0233] 2-(4-Hydroxy-3,5-dimethoxyphenyl)benzothiazole: A solution of2-(3,4,5-trimethoxyphenyl)benzothiazole (4.0 g), aluminium trichloride(4.0 g) and carbon disulphide (75 cm³) was stirred at room temperatureovernight. The reaction mixture was poured onto 20% hydrochloric acid(500 cm³) and extracted with ethyl acetate (3×50 cm³). The combinedorganic extracts were washed with water (2×250 cm³), dried (MgSO₄),filtered and the filtrate evaporated down under reduced pressure. Thesolid residue was recrystallised from ethyl acetate to give 3.0 g(75.0%) of the desired product.

[0234]¹H NMR (CDCl₃) δ_(H): 3.97 (6H, s), 7.33 (2H, s), 7.35 (1H, td),7.47 (1H, td), 7.86 (1H, d), 8.03 (1H, d).

[0235] 6-[4-(Benzothiazol-2-yl)-3,5-dimethoxyphenoxy]hexan-1-ol: Asolution of sodium hydroxide (0.4 g, 0.01 mol) in water (10 cm³) wasadded dropwise to a solution of2-(4-hydroxy-3,5-dimethoxyphenyl)benzothiazole (1.20 g, 0.0042 mol) inmethanol (100 cm³). The 6-bromohexanol (1.00 g, 0.0055 mol) was thenadded dropwise, followed by the potassium iodide (0.06 g, 0.0037 mol) inone portion. The reaction mixture was heated under reflux overnight andthe poured onto a mixture of water (100 cm³) and 10% hydrochloric acid(20 cm³). The resultant white precipitate was filtered off, pressed dryand recrystallised from ethanol to yield 1.1 g (67.9%) of the desiredalcohol.

[0236]¹H NMR (CDCl₃) δ_(H): 1.2-1.68 (8H, m), 1.72-1.87 (2H, t),3.62-3.70 (2H, t), 3.90-4.0 (6H, s), 5.28-5.32 (1H, s), 7.33 (2H, s),7.37-7.39 (1H, dd), 7.43-7.51 (1H, dd), 7.83-7.90 (1H, d), 8.01-8.08(1H, d). IR ν_(max)/cm⁻¹: 3450, 2920, 2368, 1609, 1451, 1360, 1257, 807.MS m/z: 387 (M⁺), 287 (M100), 272, 241, 212, 172, 140, 115, 83, 69.Elemental analysis: Calculated: C, 65.09; H, 6.50; N, 3.61 , S, 8.28;Found:

[0237] 2-Methylacrylic acid6-(4-benzothiazol-2-yl-2,6-dimethoxyphenoxy)hexyl ester: A solution of6-(4-benzothiazol-2-yl-2,6-dimethoxy-phenoxy)hexan-1-ol (1.10 g, 0.0038mol), methacrylic acid (1.30 g, 0.015 mol) of p-toluenesulfonic acid(0.10 g, 0.0005 mol), hydroquinone (0.10 g, 0.0009 mol) and toluene (50cm³) was heated under reflux for 48 hours in a Dean and Stark apparatusto remove water continuously and then allowed to cool. The solvent wasremoved under reduced pressure and the residue dissolved into diethylether (100 cm³). The resultant solution was washed with water (20 cm³),dried (Na₂SO₄), filtered and then evaporated down under slightly reducedpressure. The residue was recrystallised from methanol to yield 1.16 g(67.1%) of the desired product. A small amount of2,6-di-tert-butyl-4-methylphenol was added to act as an inhibitor toprevent spontaneous polymerisation.

[0238]¹H NMR (CDCl₃) δ_(H): 1.26-1.30 (8H, m), 1.68-1.83 (2H, t),1.95-2.00 (3H, s), 4.01 (6H, s), 4.15-4.20 (2H, t), 5.66-5.70 (1H, d),6.23-6.28 (1H, d), 7.33 (2H, s), 7.37-7.40 (1H, dd), 7.45-7.52 (1H, dd),7.86-7.91 (1H, d), 8.05-8.10 (1H, d). IR ν_(max)/cm⁻¹: 3440, 2920, 2370,1610, 1450, 1350, 1257, 812. MS m/z: 455 (M⁺), 401, 306, 287 (M10O),272, 244, 201, 173, 144, 108, 86, 69. Elemental analysis: Calculated: C,65.91; H, 6.42; N, 3.07, S, 7.04. Found:

[0239] Compound 27: Poly 2-Methylacrylic Acid6-(4-benzothiazol-2-yl-2,6-dimethoxyphenoxy)hexyl Ester 2-MethacrylicAcid 6-{4-[6-(4-nonylphenyl)benzothiazol-2-yl]phenoxy}hexyl Ester

[0240] Compound 27 was prepared by copolymerisation of 2-Methylacrylicacid 6-(4-benzothiazol-2-yl-2,6-dimethoxyphenoxy)hexyl ester with2-Methacrylic acid6-{4-[6-(4-nonylphenyl)benzothiazol-2-yl]phenoxy}hexyl ester in a methodanalogous to the copolymerisation step of Compound 25.

[0241] The initial reaction steps are shown in Reaction Scheme 11 andfull details are provided below.

[0242] 4-Dodecyloxybenzaldehyde: A mixture of 1-bromododecane (43.5 g,0.22 mol), 4-hydroxybenzaldehyde (25 g, 0.20 mol), potassium carbonate(69 g, 0.5 mol) and butanone (500 cm³) was heated under reflux for 24hours. The cooled solution was filtered and the filtrate evaporated downunder reduced pressure. The crude product was then distilled at 142°C.@0.6 mmHg, to give a liquid, which crystallised on cooling to yield39.2 g (67.6%) of a white solid.

[0243]¹H NMR (CDCl₃) δ_(H): 0.85-0.91 (3H, t), 1.20-1.50 (18H, m),1.76-1.85 (2H, quin), 4.00-4.20 (2H, t), 6.90-7.00 (2H, d), 7.80-7.90(2H, d), 9.90-9.92 (1H, s). IR ν_(max)/cm⁻¹: 3440, 2918, 1610, 1261,968, 834. MS m/z: 290 (M⁺), 201, 163, 135, 123(M100), 105, 97, 85, 71.Elemental analysis: Calculated: C, 78.57, H, 10.41; Found: C, 78.28, H,10.70%.

[0244] 2-(4-Dodecyloxyphenyl)benzothiazole: A solution of4-dodecyloxybenzaldehyde (37.12 g, 0.128 mol), 2-aminobenzenethiol (16g, 0.128 mol) and dimethylsulfoxide acid (200 cm³) was heated underreflux for 24 hours. The cooled solution was added to water andextracted into dichloromethane (3×50 cm³). The combined organic layerswere dried (MgSO₄), filtered and the filtrate evaporated down underreduced pressure. The solid residue was recrystallised from ethanol togive 23.1 g (45.7%) of the desired product.

[0245]¹H NMR (CDCl₃) δ_(H): 0.85-0.91 (3H, t), 1.20-1.40 (14H, m),1.42-1.52 (2H, quin), 1.60 (2H, s), 1.78-1.86 (2H, quin), 4.00-4.08 (2H,t), 6.96-7.04 (2H, d), 7.32-7.40 (1H, dd), 7.44-7.52 (1H, d), 7.85-7.93(1H, dd), 8.00-8.05 (2H, d), 8.10 (1H, d). IR ν_(max)/cm⁻¹: 3440, 2918,2360, 1610, 1261, 968, 834. MS m/z: 395(M⁺), 228, 227(M100), 198, 149,105, 97, 77, 69. Elemental analysis: Calculated: C, 75.90, H-8.41, N,3.54, S, 8.11; Found: C, 73.19, H, 8.69, N-3.55, S, 8.29%.

[0246] 6-Bromo-2-(4-dodecyloxyphenyl)benzothiazole: Bromine was addeddropwise to a solution of 2-(4-dodecyloxy-phenyl)benzothiazole (20 g,0.059 mol) and acetic acid (1,000 cm³). The reaction mixture was thenheated for a further 6 h. The cooled reaction mixture was then added toaqueous sodium metabisulphite solution (1,000 cm³). The product wasextracted using diethyl ether (3×100 cm³). The combined organic layersare washed with concentrated sodium carbonate solution (2×100 cm³) andthen with water (1×100 cm³), dried (MgSO₄), filtered and then evaporateddown under partially reduced pressure The crude product was purifiedusing column chromatography, using a 50:50 mixture ofdichloromethane/hexane an eluent to yield 2.7 g (9.6%) of the desiredproduct.

[0247]¹H NMR (CDCl₃) δ_(H): 0.85-0.91 (3H, t), 1.20-1.40 (16H, m),1.42-1.52 (2H, quin), 1.78-1.86 (2H, quin), 4.0-4.05 (2H, t), 6.96-7.01(2H, d), 7.53-7.60 (1H, dd), 7.84-7.88(1H, d), 7.97-8.00 (2H, d), 8.02(1H, d). IR ν_(max)/cm⁻¹: 3440, 2918, 2360, 1610, 1261, 968, 834. MSm/z: 475, 473 (M⁺), 395, 305(M100), 227, 197, 149, 111, 97, 83, 69.Elemental analysis: Calculated: C, 63.28; H, 6.80; N, 2.95, S 6.76;Found: C, 63.54; H, 6.99; N, 2.95, S 6.85%.

[0248] 2-(4-Dodecyloxyphenyl)-6-(4-nonylphenyl)benzothiazole: A mixtureof tetrakis(triphenylphosphine)palladium(0) (0.30 g, 0.26×10⁻³ mol),6-bromo-2-(4-dodecyloxyphenyl)benzothiazole (2.50 g, 5.27×10⁻³ mol),4-nonylbenzene boronic acid (1.57 g, 6.33×10⁻³ mol), 2M sodium carbonatesolution (25 cm³) and 1,2-dimethoxyethane (100 cm³). The reactionmixture was heated under reflux overnight. The cooled reaction mixturewas extracted with dichloromethane (2×100 cm³) and the combined organiclayers were washed with brine (2×100 cm³) and dried (MgSO₄). Afterfiltration the solvent was removed under reduced pressure and theresidue was purified by column chromatography [silica gel,dichloromethane: hexane 1:1] followed by recrystallisation from ethanolto yield 2.35 g (74.5%) of the desired product.

[0249] 2-(4-Hydroxyphenyl)-6-(4-nonylphenyl)benzothiazole: Borontribromide (0.53 cm³, 5.65×10⁻³ mol) was added dropwise to a cooled (0°C.) stirred solution of2-(4-dodecyloxyphenyl)-6-(4-nonylphenyl)benzothiazole (2.25 g, 3.76×10⁻³mol) in dichloromethane (100 cm³). The reaction mixture was stirred atroom temperature overnight, then poured onto an ice/water mixture (200g) and stirred (30 min). The reaction mixture was extracted withdichloromethane (2×75 cm³) and the combined organic layers were washedwith brine (2×100 cm³) and dried (MgSO₄). After filtration the solventwas removed under reduced pressure and the residue was purified bycolumn chromatography [silica gel, ethyl acetate:hexane 1:1] followed byrecrystallisation from ethyl acetate to yield 1.25 g (77.3%) of thedesired product.

[0250] 6-{4-[6-(4-Nonylphenyl)benzothiazol-2-yl]phenoxy}hexan-1-ol: Asolution of sodium hydroxide (0.08 g, 0.0020 mol) in water (20 cm³) wasadded dropwise to a solution of4-[6-(4-nonylphenyl)benzothiazol-2yl]phenol (0.42 g, 0.0010 mol) inmethanol (50 cm³). The 6-bromohexanol (0.18 g, 0.001 mol) was then addeddropwise, followed by the potassium iodide (0.02 g, 0.00125 mol) in oneportion. The reaction mixture was heated under reflux overnight and thepoured onto a mixture of water (100 cm³) and 10% hydrochloric acid (20cm³). The resultant precipitate was filtered off and recrystallised fromethanol to yield 0.31 g (62%) of the pure compound.

[0251]¹H NMR (CDCl₃) δ_(H): 0.85-0.91 (3H, t), 1.20-1.40 (16H, m),1.60-1.80 (6H, m), 2.60-2.70 (2H, t), 3.65-3.80 (2H, tt), 4.00-4.08(2H,t), 6.50-6.60 (1H, s), 6.90-7.00 (2H, d), 7.20-7.28 (1H, d), 7.30-7.32(1H, d), 7.53-7.60 (2H, d), 7.65-7.74 (1H, dd), 7.95-8.02 (2H, d),8.03-8.10 (2H, d). IR ν_(max)/cm⁻¹: 3402, 2920, 2368, 1609, 1451, 1257,807, 521. MS m/z: 529 (M⁺), 429, 329, 316(M100), 287, 197, 158, 139, 91,77, 69. Elemental analysis: Calculated: C, 77.08; H, 8.18; N, 2.64, S6.05; Found: C, 74.50; H, 7.14; N, 3.15, S 6.57%.

[0252] 2-Methacrylic acid6-{4-[6-(4-nonylphenyl)benzothiazol-2-yl]phenoxy}hexyl ester: A solutionof 6-{4-[6-(4-nonylphenyl)benzothiazol-2-yl]phenoxy}hexan-1-ol (0.3 g,0.0006 mol), methacrylic acid (0.2 g, 0.0023 mol), p-toluenesulfonicacid (0.015 g, 0.0008 mol), hydroquinone (0.015 g, 0.0002 mol) andtoluene (50 cm³) was heated under reflux for 48 hours in a Dean andStark apparatus to remove water continuously and then allowed to cool.The solvent was removed under reduced pressure and the residue dissolvedinto diethyl ether (50 cm³). The resultant solution was washed withwater (20 cm³), dried (Na₂SO₄), filtered and then evaporated down underslightly reduced pressure. The residue was recrystallised from methanolto yield 0.05 g (14.7%) of the desired product. A small amount of2,6-di-tert-butyl-4-methylphenol was added to act as an inhibitor toprevent self polymerisation.

[0253]¹H NMR (CDCl₃) δ_(H): 0.80-0.90 (3H, t), 1.10-1.40 (16H, m),1.45-1.80 (6H, m), 1.95-2.00 (3H, s), 2.68-2.72 (2H, t), 4.05-4.10 (2H,tt), 4.15-4.22 (2H, t), 5.65-5.71 (1H, 5.68-5.72 (1H, s), 6.20-6.24 (1H,s), 6.92-7.00 (2H, d), 7.25-7.28 (2H, d), 7.29-7.31 (1H, d), 7.55-7.60(1H, d), 7.68-7.72 (1H, dd), 7.99-8.03 (2H, d), 8.04-8.08 (2H, d). IRν_(max)/cm⁻¹: 2920, 2370, 1602, 1454, 1257, 806. MS m/z: 597 (M⁺), 544,497, 429 (M100), 316, 287, 197, 158, 105, 97, 69. Elemental analysis:Calculated: C, 76.34; H, 7.92; N, 2.34, S 5.36; Found: C, 76.12; H,8.82; N, 1.48, S 3.16%.

[0254] Thin Film Polymerisation and Evaluation

[0255] Thin films of Compounds 9 to 12 and Compounds 15 to 21 wereprepared by spin casting from a 0.5%-2% M solution in chloroform ontoquartz substrates. All sample processing was carried out in a drynitrogen filled glove box to avoid oxygen and water contamination. Thesamples were subsequently baked at 50° C. for 30 minutes, heated to 90°C. and then cooled at a rate of 0.2° C. to room temperature to form anematic glass. Polarised microscopy showed that no change was observedin the films over several months at room temperature. The films werepolymerized in a nitrogen filled chamber using light from an Argon Ionlaser. Most of the polymerization studies were carried out at 300 nmwith a constant intensity of 100 MWcm⁻² and the total fluence variedaccording to the exposure time. No photoinitiator was used. Temperaturedependent polymerization studies were carried out in a Linkham model LTS350 hot-stage driven by a TP 93 controller under flowing nitrogen gas. Asolubility test was used to find the optimum fluence: different regionsof the film were exposed to UV irradiation with different fluences andthe film was subsequently washed in chloroform for 30 s. Theunpolymerized and partially polymerized regions of the film were washedaway and PL from the remaining regions was observed on excitation withan expanded beam from the Argon Ion laser. Optical absorbancemeasurements were made using a Unicam 5625 UV-VIS spectrophotometer. PLand EL were measured in a chamber filled with dry nitrogen gas using aphotodiode array (Ocean Optics S2000) with a spectral range from 200 nmto 850 nm and a resolution of 2 nm. Films were deposited onto CaF₂substrates for Fourier Transform infra-red measurements, which werecarried out on a Perkin Elmer Paragon 1000 Spectrometer. Indium tinoxide (ITO) coated glass substrates, (Merck 15 Ω/Q) were used for ELdevices. These were cleaned using an Argon plasma.²⁰ A PDOT (EL-grade,Bayer) layer of thickness 45 nm±10% was spin-cast onto the substrate andbaked at 165° C. for 30 minutes. This formed a hole-transporting film.One or more organic films of thickness ≈45 nm were subsequentlydeposited by spin-casting and crosslinked as discussed below. Filmthicknesses were measured using a Dektak surface profiler. Aluminum wasselectively evaporated onto the films at a pressure less than 1×10⁻⁵torr using a shadow mask to form the cathode.

[0256] Photopolymerisation Details

[0257] The optimum fluences required in order to polymerize the dienemonomers (Compounds 9 to 12) efficiently with a minimum ofphotodegradation, were found to be 100 Jcm⁻², 20 Jcm⁻², 100 Jcm⁻² and300 Jcm⁻² respectively, using the solubility test. As Scheme 6 shows,the 1,6-heptadiene monomer (e.g. Compound 10) forms a network with arepeat unit containing a single ring. Its polymerization rate is equalto that of the 1,4-pentadiene monomer (e.g. Compounds 9 and 11) but theincrease of PL intensity after polymerization is less for Compound 10.This may be because of the increased flexibility of the C₇ ring in thebackbone of the crosslinked material. The 1,4-pentadiene diene monomers(Compounds 9 and 11) are homologues and differ only in the length of theflexible alkoxy-spacer part of the end-groups. The PL spectrum ofCompound 11 with the shorter spacer is significantly different to allother materials before exposure suggesting a different conformation. Thehigher fluence required to polymerize the 1,4-pentadiene monomerCompound 11 implies that the polymerization rate is dependent on thespacer length: the freedom of motion of the photopolymerizable end-groupis reduced, because of the shorter aliphatic spacer in Compound 11. Thediallylamine monomer Compound 12 has a significantly different structureto the dienes. It is much more photosensitive than the other dienemonomers because of the activation by the electron rich nitrogen atom.Scheme 6 also shows (by way of comparison) that when a methacrylatemonomer is employed the polymerization step does not involve theformation of a ring.

[0258] Photopolymerization Characteristics

[0259] The absorbance and PL spectra of 1,4-pentadiene monomer (Compound9) were measured before and after exposure with the optimum UV fluenceof 100 J cm⁻². The latter measurements were repeated after washing inchloroform for 30 s. The absorbance spectra of the unexposed and exposedfilms are almost identical and the total absorbance decreases by 15%after washing indicating that only a small amount of the material isremoved. This confirms conclusively that a predominantly insolublenetwork is formed.

[0260] The UV irradiation was carried out in the nematic glass phases atroom temperature at 300 nm. The excitation of the fluorene chromophoreis minimal at this wavelength and the absorbance is extremely low. Theexperiment was repeated using a wavelength of 350 nm near the absorbancepeak. Although the number of absorbed photons is far greater at 350 nm,a similar fluence is required to form an insoluble network. Furthermoreexcitation at 350 nm results in some photodegradation. UVphotopolymerization was also carried out at 300 nm at temperatures of50° C., 65° C. and 80° C. all in the nematic phase. It was anticipatedthat the polymerization rate would increase, when the photoreactivemesogens were irradiated in the more mobile nematic phase. However, thefluence required to form the crosslinked network was independent oftemperature, within the resolution of our solubility test. Furthermore,the integrated PL intensity from the crosslinked network decreases withtemperature indicating a temperature dependent photodegradation.

[0261] Bilayer Electroluminescent Devices

[0262] Bilayer electroluminescent devices were prepared by spin-castingthe 1,4-pentadiene monomer (Compound 9) onto a hole-transporting PEDTlayer. The diene functioned as the light-emitting andelectron-transporting material in the stable nematic glassy state.Equivalent devices using cross-linked networks formed from Compound 9 byphotopolymerisation with UV were also fabricated on the same substrateunder identical conditions and the EL properties of both types ofdevices evaluated and compared. The fabrication of such bilayer OLEDs isfacilitated by the fact that the hole-transporting PEDT layer isinsoluble in the organic solvent used to deposit the electroluminescentand electron-transporting reactive mesogen (Compound 9). Half of thelayer of Compound 9 was photopolymerized using optimum conditions andthe other half was left unexposed so that EL devices incorporatingeither the nematic glass or the cross-linked polymer network could bedirectly compared on the same substrate under identical conditions.Aluminum cathodes were deposited onto both the cross-linked and noncross-linked regions. Polarized electroluminescent devices were preparedby the polymerization of uniformly aligned Compound 9 achieved bydepositing it onto a photoalignment layer doped with a hole transportingmolecule. In these devices external quantum efficiencies of 1.4% wereobtained for electroluminescence at 80 cd m⁻². Three layer devices werealso prepared by spin-casting an electron transporting polymer (Compound13), which shows a broad featureless blue emission, on top of thecrosslinked nematic polymer network. In the case of both the three layerand bilayer devices the luminescence originates from the cross-linkedpolymer network of the 1,4-pentadiene monomer (Compound 9). Theincreased brightness of the three-layer device may result from animproved balance of electron and hole injection and/or from a shift ofthe recombination region away from the absorbing cathode.

[0263] Multilayer Device

[0264] A multilayer device configuration was implemented as illustratedin FIG. 2. A glass substrate 30 (12 mm×12 mm×1 mm) coated with a layerof indium tin oxide 32 (ITO) was cleaned via oxygen plasma etching.Scanning electron microscopy revealed an improvement in the surfacesmoothness by using this process which also results in a beneficiallowering of the ITO work function. The ITO was coated with two strips(˜2 mm) of polyimide 34 along opposite edges of the substrate thencovered with a polyethylene dioxthiophene/polystyrene sulfonate(PEDT/PSS) EL-grade layer 36 of thickness 45±5 nm deposited byspin-coating. The layer 36 was baked at 165° C. for 30 min in order tocure the PEDT/PSS and remove any volatile contaminants. The dopedpolymer blend of Compounds 2 and 8 was spun from a 0.5% solution incyclopentanone forming an alignment layer 40 of thickness ˜20 nm. Thisformed the hole-injecting aligning interface after exposure to linearlypolarized CV from an argon ion laser tuned to 300 nm. Aliquid-crystalline luminescent layer 50 of Compound 9 was then spun castfrom a chloroform solution forming a film of ˜10 nm thickness. A furtherbake at 50° C. for 30 min was employed to drive off any residualsolvent. The sample was heated to 100° C. and slowly cooled at 02°C./min to room temperature to achieve macroscopic alignment ofchromophores in the nematic glass phase. Irradiation with UV light at300 nm from an argon ion laser was used to induce crosslinking of thephotoactive end-groups of the Compound 9 to form an insoluble andintractable layer. No photoinitiator was used hence minimizing continuedphotoreaction during the device lifetime. Aluminium electrodes 50 werevapor-deposited under a vacuum of 100 mbar or better and silver pastedots 52 applied for electrical contact. A silver paste contact 54 wasalso applied for contact with the indium tin oxide base electrode. Thisentire fabrication process was carried out under dry nitrogen of puritygreater than 99.99%. Film thickness was measured using a Dektak STsurface profiler.

[0265] The samples were mounted for testing within a nitrogen-filledchamber with spring-loaded probes. The polymide strips form a protectivelayer preventing the spring-loaded test probes from pushing through thevarious layers. Optical absorbance measurements were taken using aUnicam UV-vis spectrometer with a polarizer (Ealing Polarcaot 105 UV-viscode 23-2363) in the beam. The spectrometer's polarization bias wastaken into account and dichroic ratios were obtained by comparing maximaat around 370-380 nm.

[0266] Luminescence/voltage measurements were taken using aphotomultiplier tube (EMI 6097B with S11 type photocathode) and Keithley196 multimeter with computer control. Polarized EL measurements weretaken using a photodiode array (Ocean Optics S2000, 200-850 nm bandwidth2 nm resolution) and polarizer as described above. The polarization biasof the spectrometer was eliminated by use of an input fiber (fusedsilica 100 μm diameter) ensuring complete depolarisation of light intothe instrument.

[0267] Monochrome Backlight

[0268]FIG. 3 shows a schematic representation of a polarised lightmonochrome backlight used to illuminate a twisted nematic liquid crystaldisplay. The arrows indicate the polarisation direction. An inertsubstrate 30 (e.g. glass coated with a layer of indium tin oxide (ITO)as in FIG. 2) is provided with a layer 50 of a polarised light emittingpolymer (e.g. comprising Compound 9 as in FIG. 2). The assembly furtherincludes a clean up polariser 60 comprising a high transmission lowpolarisation efficiency polariser; a twisted nematic liquid crystaldisplay 70; and a front polariser 80. It will be appreciated that thelight emitting polymer layer 50 acts as a light source for the liquidcrystal display 70.

[0269] Polarised Light Sequential Tricolor Backlight

[0270]FIG. 3 schematic of a polarised light sequential red, green andblue light emitting backlight used to illuminate a fast liquid crystaldisplay (ferroelectric display). The arrows indicate the polarisationdirection. An inert substrate 30 (e.g. glass coated with a layer ofindium tin oxide (ITO) as in FIG. 2) is respectively provided with red52, green 54 and blue 56 striped layers of a polarised light emittingpolymer (e.g. comprising Compound 9 as in FIG. 2 and a suitable dyemolecule as a dopant). The assembly further includes a clean uppolariser 60 comprising a high transmission low polarisation efficiencypolariser; a fast (ferroelectric) liquid crystal display 70; and a frontpolariser 80. It will be appreciated that the striped light emittingpolymer layer 52, 54, 56 acts as a light source for the fast liquidcrystal display 70. The sequential emission of the RGB stripescorresponds with the appropriate colour image on the fast liquid crystaldisplay. Thus, a colour display is seen.

[0271] Alignment Characteristics

[0272] The PL polarization ratio (PL_(η)/PL_(⊥)) of the aligned polymerformed from Compound 9 in its nematic glass phase can be taken as ameasure of the alignment quality. Optimum alignment is obtained with theundoped alignment layer for an incident fluence of 50 mJ cm⁻². Thealignment quality deteriorates when higher fluences are used. This isexpected because there are competing LC-surface interactions givingparallel and perpendicular alignment respectively. When the dopantconcentration is 40% or higher there is a detrimental effect onalignment. However with concentrations up to 30% the polarization ratioof emitted light is not severely effected although higher fluences arerequired to obtain optimum alignment. The EL intensity reaches its peakfor the ˜50% mixture. A 30% mixture offers a good compromise inbalancing the output luminescence intensity and polarization ratio. Fromthese conditions and using the 30% doped layer we have observed strongoptical dichroism in the absorbance (D˜6.5) and obtained PL polarizationratios of 8:1.

[0273] Electroluminescence Characteristics

[0274] Devices made with Compound 9 in the nematic glassy state showedpoor EL polarization ratios because the low glass transition temperaturecompromised the alignment stability. Much better performance wasachieved when compound 9 was crosslinked.

[0275] A brightness of 60 cd m⁻² (measured without polarizer) wasobtained at a drive voltage of 11V. The threshold voltage, ELpolarization ratio and intensity all depend on the composition of thealignment layer. A luminance of 90 cd m⁻² was obtained from a 50% dopeddevice but with a reduction in the EL polarization ratio. Conversely apolarized EL ratio of 11:1 is found from a 20% doped device but withlower brightness. A threshold voltage of 2V is found for the device witha hole-transporting layer with 100% of the dopant comprising compound 8.Clearly a photo-alignment polymer optimised for both alignment andhole-transporting properties would improve device performance. Thiscould be achieved using a co-polymer incorporating both linear rod-likehole-transporting and photoactive side chains.

1. A liquid crystal alignment layer comprising an alignment layer; andchemically bound to said alignment layer, a transport material.
 2. Aliquid crystal alignment layer according to claim 1, wherein thealignment layer is a photoalignment layer.
 3. A liquid crystal alignmentlayer according to claim 2, wherein the photoalignment layer comprises achromophore attached to a sidechain polymer backbone by a flexiblespacer entity.
 4. A liquid crystal alignment layer according to claim 3,wherein the chromophore is selected from the group consisting ofcinnamates, coumarins and any derivatives thereof.
 5. A liquid crystalalignment layer according to claim 4, wherein the chromophore is the7-hydroxycoumarin compound having the formula:


6. A liquid crystal alignment layer according to claim 2, wherein thephotoalignment layer is photocurable.
 7. A liquid crystal alignmentlayer according to claim 1, wherein the alignment layer is a polyimidelayer.
 8. A liquid crystal alignment layer according to claim 7, whereinthe polyimide layer is in the form of a photoaligned polyimide layer. 9.A liquid crystal alignment layer according to claim 7, wherein thepolyimide layer is in the form of a rubbed polyimide layer.
 10. A liquidcrystal alignment layer according to claim 1, wherein the alignmentlayer is a nylon layer.
 11. A liquid crystal alignment layer accordingto claim 1, wherein the alignment layer is a cross-linked polymer layer.12. A liquid crystal alignment layer according to claim 11, wherein thecross-linked polymer layer is obtainable by deposition of a curablereactive monomer/oligomer and subsequent photo or thermal cross-linkingthereof.
 13. A liquid crystal alignment layer according to claim 1,wherein the alignment layer comprises a side chain liquid crystalpolymer.
 14. A liquid crystal alignment layer according to claim 13,wherein the side chain liquid polymer has the formula:


15. A liquid crystal alignment layer according to claim 1, wherein thealignment layer comprises a reactive liquid crystal obtainable from areactive mesogen.
 16. A liquid crystal alignment layer according toclaim 15, wherein the reactive mesogen has the formula:


17. A liquid crystal alignment layer according to claim 1, wherein thealignment layer comprises a grating structure.
 18. A liquid crystalalignment layer according to claim 1, wherein said transport materialincreases the electrical conductivity of the alignment layer.
 19. Aliquid crystal alignment layer according to claim 18, wherein thealignment layer is an electrical insulator in the absence of thetransport material.
 20. A liquid crystal alignment layer according toclaim 1, wherein the transport material is selected from the groupconsisting of an ion transport compound, a hole transport compound, anelectron transport compound and any mixtures thereof.
 21. A liquidcrystal alignment layer according to claim 20, wherein the ion transportcompound is selected from the group consisting of mono-reactive iontransport materials, di-reactive ion transport materials and anymixtures thereof.
 22. A liquid crystal alignment layer according toclaim 20, wherein the ion transport compound is a hole transportcompound including a triarylamine.
 23. A liquid crystal alignment layeraccording to claim 1, wherein the alignment polymer is in the form of apolymer network and the transport material is a bound component of saidnetwork.
 24. A liquid crystal alignment layer according to claim 23,wherein the alignment layer is a photoalignment layer having a lightemitting polymer aligned thereon.
 25. A liquid crystal alignment layeraccording to claim 1, wherein the alignment layer and the transportmaterial are comprised as a co-polymer.
 26. A liquid crystal alignmentlayer according to claim 25, wherein said co-polymer is obtainable byco-polymerising a coumarin alignment layer with a transport materialcomprising a methacrylate end-group.
 27. A liquid crystal alignmentlayer according to claim 26, wherein the co-polymer is selected from thegroup consisting of:

wherein, x is greater than 0 and less than 1; and n is from 5 to 500.28. A liquid crystal alignment layer according to claim 1, wherein thelayer has a thickness of from 10 to 500 nm.
 29. A liquid crystal cellcomprising an inert substrate; and on said inert substrate, a liquidcrystal alignment layer according to any of claims 1 to
 28. 30. A liquidcrystal cell according to claim 29, wherein the inert substrate isselected from the group consisting of glass and plastic substrates. 31.A liquid crystal cell according to claim 30, wherein the inert substrateis an indium tin oxide (ITO) coated glass substrate.
 32. Method offorming a liquid crystal cell according to claim 28, comprising reactingthe constituents of the alignment layer and the transport material toform a chemical bond therebetween; and subsequently applying the layerto the substrate.
 33. Method of forming a liquid crystal cell accordingto claim 28, comprising applying the constituents of the alignment layerand the transport material to the substrate; and subsequently reactingsaid constituents in situ to form a chemical bond therebetween.
 34. Aliquid crystal display comprising a driver for driving the display; anda liquid crystal cell according to claim
 28. 35. A liquid crystaldisplay according to claim 34, in the form of a ferroelectric liquidcrystal (FLC) display.